Update function {#update-function}

Bertin.js is a JavaScript library for visualizing geospatial data and make thematic maps for the web.

The project is under active development. Some of features and options are subject to change. We welcome contributions of all kinds: bug reports, code contributions and documentation. A todo list of the next improvements is available here.

Introduction
Who is Bertin?
Installation
Usage
Drawing a map
Map types
Map components
Custom Layer
Geojson properties selections
Other functions
Update function
Bonus: a cheat sheet

bertin is an easy to use JavaScript library mainly based on D3.js makes creating thematic maps simple. The principle is to work with layers stacked on top of one other. Much like in Geographic Information Software (GIS) software, Bertin.js displays layers with a specific hierarchy. The layer at bottom are rendered and then followed by the layer right above it. Some of the layers are used to display various components of a map, some of common layers are: header, footer, graticule, outline, choro, typo, prop, shadow, scalebar, text etc.

The draw() function is the most important function of the library. It allows you to draw all types of maps.
The update() function allows you to modify specific elements of the map without the need to redraw everything. Only the parameters underlined in the documentation can be modified through this function.

Cheat Sheet

Who is Bertin? {#who-is-bertin}

Jacques Bertin (1918-2010) was a French cartographer, whose major contribution was a theoretical and practical reflection on all graphic representations (diagrams, maps and graphs), forming the subject of a fundamental treatise, Graphic Semiology, originally published in 1967. Bertin's influence remains strong not only in academics, teaching of cartography today, but also among statisticians and data visualization specialists.

Installation {#installation}

In browser

Latest version

<script
  src="https://cdn.jsdelivr.net/npm/bertin"
  charset="utf-8"
></script>

Pinned version

<script src="https://cdn.jsdelivr.net/npm/bertin@1.7" charset="utf-8"></script>

In Observable

Latest version

bertin = require("bertin");

Pinned version

bertin = require("bertin@1.7");

In Quarto

In Quarto, you can use bertin with ojs cells. This allows to combine analyses in R or Python with visualizations made with bertin. An example is available here

Usage {#usage}

In browser

<script src="https://cdn.jsdelivr.net/npm/d3@7"></script>
<script src="https://cdn.jsdelivr.net/npm/bertin"></script>

<script>
  let geojson =
    "https://raw.githubusercontent.com/neocarto/bertin/main/data/world.geojson";

  d3.json(geojson).then((r) =>
    document.body.appendChild(
      bertin.draw({
        params: {
          projection: "VanDerGrinten4",
          clip: true,
        },
        layers: [
          { geojson: r, tooltip: ["$ISO3", "$NAMEen"] },
          { type: "outline" },
          { type: "graticule" },
        ],
      })
    )
  );
</script>

See examples: Example 1, Example 2 and Example 3.

In Observable Notebook

The bertin.js library is really easy to use within an Observable notebook. You'll find many examples in this notebook collection. Feel free to fork, copy, modify with your own data.

Drawing a map {#drawing-a-map}

draw() is the main function of the library. It allows you to make various thematic maps. It allows to display and overlay different types of layers listed below. The layers written on top are displayed first. Source Example

Global parameters

In the section params, we define the global parameters of the map: its size, projection, background color, etc. To have access to a large number of projections, you will need to load the d3-geo-projection@4 library. This section is optional.

Code

bertin.draw({
  params: {
    projection: d3.geoBertin1953(),
    width: 750,
  },
  layers: [...]
})

A globe view is available for some types of layers: simple (with symbol_shift == 0), spikes, bubble (with dorling == true), geolines, graticule, inner, missing, shadow, tissot, dotdensity and label.

To use it, you juste have to use "globe" as projection. You can also define the center og the map by using "globe(x,y,rotate)"

Parameters

projection: a d3 function or string defining the map projection. Refer d3-geo-projection and spatialreference.org for more detailed explanation. (default: d3.geoEquirectangular() except if you use tiles. in this case, the projection is automatically set to d3.geoMercator()). Moreover, if you define projection as "user", you can display a basemap already projected. Example. Note alsa that custom projections are available. Try "Polar", "Spilhaus" or "HoaXiaoguang".
width: width of the map (default:1000);
extent: a feature or a bbox array defining the extent e.g. a country or [[112, -43],[153, -9]] (default: null)
margin: margin around features to be displayed. You can specify a single value or an array [top, right, bottom, left]. (default: 1)
background: color of the background (default: "none")
clip: a boolean to avoid artifacts of discontinuous projection (default: "false")
reverse: a boolean. By default, the layer placed on the top of the code is display on the top of the map. With reverse = true, your can reverse this order (default: false).

Map types {#map-types}

Simple layer

The layer type allows to display a simple geojson layer (points, lines or polygons). Source. Example 1 and Example 2.

Code

bertin.draw({
  layers: [
    {
      type: "layer",
      geojson: *a geojson here*,
      fill: "#e6acdf",
    }
  ]
})

Parameters

geojson: a geojson (compulsory)
rewind: a boolean. If true, the geojson is rewinded for a proper display (default: false)
fill

: fill color (default: a random color)
stroke

: stroke color (default: "white")
strokeWidth

stroke width (default:0.5)
strokeLinecap

: stroke-linecap (default:"round")
strokeLinejoin

: stroke-linejoin (default:"round")
strokeDasharray

: stroke-dasharray (default:"none")
fillOpacity

: fill opacity (default:1)
strokeOpacity

: stroke opacity (default:1)
symbol

: if it is a dot layer, the type of symbol. "circle", "cross", "diamond", "square", "star", "triangle", "wye" (default: "circle")
symbol_size

: if it is a dot layer, a number indicating the size of the symbol (default: 5)
symbol_shift: if it is a dot layer, use a value > 0 to switch symbols and avoid overlay (default: 0)
symbol_iteration: Number of iteration to shift symbols (default: 200)
viewof: Boolean to use this layer as an Observable view. See explanations (default: false)

Parameters of the legend

leg_x: position in x (if this value is not filled, the legend is not displayed)
leg_y: position in y (if this value is not filled, the legend is not displayed)
leg_w: width of the box (default: 30)
leg_h: height of the box (default: 20)
leg_title: title of the legend (default: null)
leg_text: text of the box (default: "leg_text")
leg_fontSize: title legend font size (default: 14)
leg_fontSize2: values font size (default: 10)
leg_fill: color of the box (same as the layer displayed)
leg_stroke: stroke of the box (default: "black")
leg_strokeWidth: stroke-width (default: 0.5)
leg_fillOpacity: stroke opacity (same as the layer displayed)
leg_txtcol: color of the text (default: "#363636")

Choropleth

The choro type aims to draw Choropleth maps. This kind of representation is especially suitable for relative quantitative data (rates, indices, densities). The choro type can be applied to the fill or stroke property of a simple layer. Example.

Code

bertin.draw({
  layers: [
    {
      type: "layer",
      geojson: data,
      fill: {
        type: "choro",
        values: "gdppc",
        nbreaks: 5,
        method: "quantile",
        colors: "RdYlGn",
        leg_round: -1,
        leg_title: `GDP per inh (in $)`,
        leg_x: 100,
        leg_y: 200
      }
  ]
})

Parameters

values

: a string corresponding to the targeted variable in the properties (compulsory)
nbreaks

: Number of classes (default:5)
breaks

: Class breaks (default:null)
colors

: An array of colors or a palette of colors (Blues", "Greens", "Greys", "Oranges", "Purples", "Reds", "BrBG", "PRGn", "PiYG", "PuOr", "RdBu", "RdYlBu", "RdYlGn", "Spectral","Turbo","Viridis","Inferno", "Magma", "Plasma", "Cividis", "Warm", "Cool", "CubehelixDefault", "BuGn", "BuPu", "GnBu", "OrRd", "PuBuGn", "PuBu", "PuRd", "RdPu", "YlGnBu", "YlGn", "YlOrBr", "YlOrRd", "Rainbow", "Sinebow". default: Blues) See
method

: A method of classification. "quantile", "q6", "equal", "msd" (mean standard deviation), "jenks", "geometric", "headtail" or "pretty" (default: "quantile"). See statsbreaks example for method implementation in action.
middle

: for msd method only. middle class or not (default:false);
k

: for msd method only. number of sd. (default:1);
col_missing

: Color for missing values (default "#f5f5f5")
txt_missing

: Text for missing values (default "No data")
stroke

: stroke color (default: "white")
strokeWidth

: Stroke width (default: 0.5)
fillOpacity

: Fill opacity (default: 1)

Parameters of the legend

leg_x

: position in x (if this value is not filled, the legend is not displayed)
leg_y

: position in y (if this value is not filled, the legend is not displayed)
leg_w

: width of the box (default: 30)
leg_h

: height of the box (default:20)
leg_text

: text of the box (default: "leg_text")
leg_fontSize

: text font size (default: 10)
leg_fill

: color of the box (same as the layer displayed)
leg_stroke

: stroke of the box (default: "black")
leg_strokeWidth

: stroke-width (default: 0.5)
leg_fillOpacity

: stroke opacity (same as the layer displayed)
leg_txtcol

: color of the text (default: "#363636")
leg_round

: Number of digits (default: undefined)

Typology

The typo type allows to realize a qualitative map. The choro type can be applied to the fill or stroke property of a simple layer. Example.

Code

bertin.draw({
  layers: [
    {
      type: "layer",
      geojson: data,
      fill: {
        type: "typo",
        values: "region",
        pal: "Tableau10",
        tooltip: ["$region", "$name"],
        leg_title: `The Continents`,
        leg_x: 55,
        leg_y: 180
      }
    }
  ]
})

Parameters

values

: a string corresponding to the targeted variable in the properties (compulsory)
colors

: An array containing n colors for n types, or a a palette of categorical colors (default: "Tableau10"). See the handy color scheme reference for full list of palettes.
order

: an array of values to set the order of the colors
col_missing

: Color for missing values (default "#f5f5f5")
txt_missing

: Text for missing values (default "No data")
stroke

: stroke color (default: "white")
strokeWidth

: Stroke width (default: 0.5)
fillOpacity

: Fill opacity (default: 1)

Parameters of the legend

leg_x

: position in x (if this value is not filled, the legend is not displayed)
leg_y

: position in y (if this value is not filled, the legend is not displayed)
leg_w

: width of the box (default: 30)
leg_h

: height of the box (default:20)
leg_title

: title of the legend (default; null)
leg_fontSize

: title legend font size (default: 14)
leg_fontSize2

: values font size (default: 10)
leg_stroke

: stroke of the box (default: "black")
leg_strokeWidth

: stroke-width (default: 0.5)
leg_fillOpacity

: stroke opacity (same as the layer displayed)
leg_txtcol

: color of the text (default: "#363636")

Bubble

The bubble type is used to draw a map by proportional circles. Source, Example.

Code

bertin.draw({
  layers: [
    {
      type: "bubble",
      geojson: countries,
      values: "pop",
      k: 60,
      tooltip: ["$country", "$pop", "(inh.)"],
    },
  ],
});

Parameters

geojson: a geojson (compulsory)
rewind: a boolean. If true, the geojson is rewinded for a proper display (default: false)
values

: a string corresponding to the targeted variable in the properties(compulsory)
k

: size of the largest circle (default:50)
fixmax: Max value to fix the size of the biggest circle, in order to make maps comparable (default:undefined)
fill

: fill color (default: random color)
stroke

: stroke color (default: "white")
strokeWidth

: stroke width (default: 0.5)
fillOpacity

: fill opacity (default: 1)
dorling

: a boolean (default:false)
iteration: an integer to define the number of iteration for the Dorling method (default: 200)
tooltip: an array of values defining what to display within the tooltip. If you use a $, the value within the geojson is displayed. Example.
viewof: Boolean to use this layer as an Observable view. See explanations (default: false)

Parameters of the legend

leg_x: position in x (if this value is not filled, the legend is not displayed)
leg_y: position in y (if this value is not filled, the legend is not displayed)
leg_fill: color of the circles (default: "none")
leg_stroke: stroke of the circles (default: "black")
leg_strokeWidth: stoke-width (default: 0.8)
leg_txtcol: color of the text (default: "#363636")
leg_title: title of the legend (default var_data)
leg_round: number of digits after the decimal point (default: undefined)
leg_divisor: A number to divide to the values in the legend. For example, 1000 is used to convert units to thousands. 1000000 allows to convert units into millions (default: 1).
leg_fontSize: title legend font size (default: 14)
leg_fontSize2: values font size (default: 10)

Square

The square type is used to draw a map by proportional squares. Source, Example.

Code

bertin.draw({
  layers: [
    {
      type: "square",
      geojson: countries,
      values: "pop",
      k: 60,
      tooltip: ["$country", "$pop", "(inh.)"],
    },
  ],
});

Parameters

geojson: a geojson (compulsory)
rewind: a boolean. If true, the geojson is rewinded for a proper display (default: false)
values

: a string corresponding to the targeted variable in the properties(compulsory)
k

: size of the largest circle (default:50)
fixmax: Max value to fix the size of the biggest circle, in order to make maps comparable (default:undefined)
fill

: fill color (default: random color)
stroke

: stroke color (default: "white")
strokeWidth

: stroke width (default: 0.5)
fillOpacity

: fill opacity (default: 1)
demers

: a boolean to avoid overlay. Dorling parameter works also (default:false) - EXPERIMENTAL
iteration: an integer to define the number of iteration for the Dorling method (default: 200)
tooltip: an array of values defining what to display within the tooltip. If you use a $, the value within the geojson is displayed. Example.
viewof: Boolean to use this layer as an Observable view. See explanations (default: false)

Parameters of the legend

leg_x: position in x (if this value is not filled, the legend is not displayed)
leg_y: position in y (if this value is not filled, the legend is not displayed)
leg_fill: color of the circles (default: "none")
leg_stroke: stroke of the circles (default: "black")
leg_strokeWidth: stoke-width (default: 0.8)
leg_txtcol: color of the text (default: "#363636")
leg_title: title of the legend (default var_data)
leg_round: number of digits after the decimal point (default: undefined)
leg_divisor: A number to divide to the values in the legend. For example, 1000 is used to convert units to thousands. 1000000 allows to convert units into millions (default: 1).
leg_fontSize: title legend font size (default: 14)
leg_fontSize2: values font size (default: 10)

Regular Bubble

The regularbubble type is used to draw a map by proportional circles in a regular grid, from absolute quantitative data. Source, Example and methodology.

Code

bertin.draw({
  layers: [
    {
      type: "regularbubble",
      geojson: countries,
      step:20,
      values: "pop",
      k: 60,
      tooltip: "$value",
    },
  ],
});

Parameters

step: Gap between the points (default:20)
operator: "sum" for absolute quantitative data or "mean" for relative data (default: "sum". highly recommended)
geoprocessing: "intersection" (intersection between polygons and grid squares. Assignment of values in proportion to the intersected area) or "dotinpoly" (considers each grid square and assigns the value of the underlying polygon or the weighted average of intersecting polygons. ). (Default: "intersection")
blur: radius of the kernel defined in d3.blur2 (default: 0)

All other parameters are the same as for the bubble layer

Regular Square

The regularsquare type is used to draw a map by proportional squares in a regular grid, from absolute quantitative data. Source, Example and methodology.

Code

bertin.draw({
  layers: [
    {
      type: "regularsquare",
      geojson: countries,
      step:20,
      values: "pop",
      k: 60,
      tooltip: "$value",
    },
  ],
});

Parameters

step: Gap between the points (default:20)
operator: "sum" for absolute quantitative data or "mean" for relative data (default: "sum". highly recommended)
geoprocessing: "intersection" (intersection between polygons and grid squares. Assignment of values in proportion to the intersected area) or "dotinpoly" (considers each grid square and assigns the value of the underlying polygon or the weighted average of intersecting polygons. ). (Default: "intersection")
blur: radius of the kernel defined in d3.blur2 (default: 0)

All other parameters are the same as for the square layer

Regular grid

The regulargrid type is a way to transform an irregular geographic mesh into a regular mesh. The values of the grid cells are obtained in proportion to the intersected surface. This representation mode is only suitable for absolute quantitative data. But you can use 2 quantitative data to compute a ratio Source, Example and methodology.

Code

bertin.draw({
  layers: [
    {
      type: "regulargrid",
      geojson: countries,
      step:20,
      values: "pop",
      fill:{
        nbreaks: 6,
        method: "quantile",
        colors: "Blues"
      }
      tooltip: "$value",
    },
  ],
});

Parameters

step: Gap between the points (default:20)
operator: "sum" for absolute quantitative data or "mean" for relative data (default: "sum")
geoprocessing: "intersection" (intersection between polygons and grid squares. Assignment of values in proportion to the intersected area) or "dotinpoly" (considers each grid square and assigns the value of the underlying polygon or the weighted average of intersecting polygons. ). (Default: "intersection")
blur: radius of the kernel defined in d3.blur2 (default: 0)

All other parameters are the same as for choropleth maps

Stock and ratio

In thematic mapping, we often have to represent an absolute quantitative data with a size variation and relative quantitative data with color variations. For this we can use the bubble type and the choro type together. Example.

Code

bertin.draw({
  params: { projection: d3.geoPolyhedralWaterman() },
  layers: [
    {
      type: "bubble",
      geojson: data,
      leg_round: -2,
      values: "pop",
      fill: {
        type: "choro",
        method: "quantile",
        nbreaks: 5,
        values: "gdppc",
        pal: "RdYlGn",
      },
    },
  ],
});

Stock and typo

In thematic mapping, we often have to represent an absolute quantitative data with a size variation and relative quantitative data with color variations. For this we can use the bubble type and the typo type together. Example.

Code

bertin.draw({
  layers: [
    {
      type: "bubble",
      geojson: data,
      values: "pop",
      fill: {
        type: "typo",
        values: "region",
      },
    },
  ],
});

Dorling cartogram

The dorling parameter can be used with the bubble type to design a Dorling cartogram. Example.

Code

bertin.draw({
  layers: [
    {
      type: "bubble",
      geojson: data,
      values: "pop",
      k: k,
      dorling: true,
      iteration: 100,
      fill: "#E95B40",
    },
  ],
});

Dot cartogram

The dotcartogram type is a method of map representation that follows Dorling's cartograms and dot density maps. The data from each territorial unit are dissolved in such a way that a dot represents a constant quantity, the same on the whole map. Source Example.

Code

bertin.draw({
  params: { projection: d3.geoBertin1953() },
  layers: [
    {
      type: "dotcartogram",
      geojson: data,
      onedot: 200000000000,
      iteration: 200,
      values: "gdp",
      radius: radius,
      span: span,
      leg_fill: "none",
      leg_stroke: "black",
      leg_strokeWidth: 1.5,
      leg_x: 800,
      leg_y: 450,
      leg_title: `GDP by world region`,
      leg_txt: "200 billion $",
      fill: "red",
      tooltip: ["$name", "$region"],
    },
  ],
});

Parameters

geojson: a geojson (compulsory)
rewind: a boolean. If true, the geojson is rewinded for a proper display (default: false)
values: a string corresponding to the targeted variable in the properties(compulsory)
radius: radius of dots (default:4)
nbmax: number max of circles on the map (default:200)
onedot: dot value (if onedot is filled, nbmax is useless)
span: spacing between dots (default 0.5)
fill: fill color (default: random color)
stroke: stroke color (default: "white")
strokeWidth: stroke width (default: 0.5)
fillOpacity: fill opacity (default: 1)
tooltip an array of values defining what to display within the tooltip. If you use a $, the value within the geojson is displayed.
iteration an integer to define the number of iteration for the Dorling method (default 200)
viewof: Boolean to use this layer as an Observable view. See explanations (default: false)

Parameters of the legend

leg_x: position in x (if this value is not filled, the legend is not displayed)
leg_y: position in y (if this value is not filled, the legend is not displayed)
leg_fill: color of the circles (default: "none")
leg_stroke: stroke of the circles (default: "black")
leg_strokeWidth: stoke-width (default: 0.8)
leg_txtcol: color of the text (default: "#363636")
leg_title: title of the legend (default var_data)
leg_txt: text in the legend (default onedot value)
leg_fontSize: title legend font size (default: 14)
leg_fontSize2: text font size (default: 10)

Mushroom

The mushroom type is used to draw a map with 2 superposed proportional semi-circles. This type of representation can be used when two data with the same order of magnitude need to be compressed. Source, Example.

Code

bertin.draw({
  layers: [
    {
      type: "mushroom",
      geojson: mygeojson,
      top_values: "gdp_pct",
      bottom_values: "pop_pct",
      bottom_tooltip: ["name", "pop", "(thousands inh.)"],
      top_tooltip: ["name", "gdp", "(million $)"],
    },
  ],
});

Parameters

geojson: a geojson (compulsory)
rewind: a boolean. If true, the geojson is rewinded for a proper display (default: false)
top_values: a string corresponding to the targeted top variable in the properties (compulsory)
bottom_values: a string corresponding to the targeted bottom variable in the properties(compulsory)
top_fill: top fill color (default: "#d64f4f")
bottom_fill: bottom fill color (default: "#4fabd6")
k: size of the largest semi circle (default:50)
stroke: stroke color (default: "white")
strokeWidth: stroke width (default: 0.5)
fillOpacity: fill opacity (default: 1)
strokeOpacity: stroke opacity (default: 1)
top_tooltip: an array of values defining what to display within the tooltip. If you use a $, the value within the geojson is displayed.
bottom_tooltip: an array of values defining what to display within the tooltip. If you use a $, the value within the geojson is displayed.
viewof: Boolean to use this layer as an Observable view. See explanations (default: false)

Parameters of the legend

leg_x: position in x (if this value is not filled, the legend is not displayed)
leg_y: position in y (if this value is not filled, the legend is not displayed)
leg_fontSize: title legend font size (default: 14)
leg_fontSize2: values font size (default: 10)
leg_round: number of digits after the decimal point (default: undefined)
leg_txtcol: color of the text (default: "#363636")
leg_title: title of the legend (default "Title, year")
leg_stroke: stroke of the circles (default: "black")
leg_top_txt title for the top variable (default top_var)
leg_bottom_txt title for the bottom variable (default bottom_var)
leg_top_fill color of top semi circles (default same as top_fill)
leg_bottom_fill color of bottom semi circles (default same as bottom_fill)
leg_strokeWidth stroke width of elements in the legend (default 0.8)

Dot Density

The dotdensity type allows to display a doty density layer geojson layer from polygons and attribute data. Source. Example

Code

bertin.draw({
  layers: [
    {
      type: "dotdensity",
      geojson: *a geojson here (polygon)*,
      values: *a fiel here*
      dotvalue: *a number*,
    }
  ]
})

Parameters

geojson: a geojson polygons or Multipolygons (compulsory)
rewind: a boolean. If true, the geojson is rewinded for a proper display (default: false)
values: a string corresponding to the targeted variable in the properties(compulsory)
dotvalue: a number representing the value of each point (default: a computed number so that there are no more than 1000 dots on the map.)
fill: fill color (default: a random color)
stroke: stroke color (default: "white")
strokeWidth stroke width (default:0.5)
fillOpacity: fill opacity (default:1)
strokeOpacity: stroke opacity (default:1)
symbol: if it is a dot layer, the type of symbol. "circle", "cross", "diamond", "square", "star", "triangle", "wye" (default: "circle")
symbol_size: if it is a dot layer, a number indicating the size of the symbol (default: 5)
symbol_shift: if it is a dot layer, use a value > 0 to switch symbols and avoid overlay (default: 0)
symbol_iteration: Number of iteration to shift symbols (default: 200)

Parameters of the legend

leg_x: position in x (if this value is not filled, the legend is not displayed)
leg_y: position in y (if this value is not filled, the legend is not displayed)
leg_w: width of the box (default: 30)
leg_h: height of the box (default:20)
leg_title: title of the legend (default: null)
leg_text: text in the legend (default: dot value)
leg_fontSize: title legend font size (default: 14)
leg_fontSize2: values font size (default: 10)
leg_fill: color of the box (same as the layer displayed)
leg_stroke: stroke of the box (default: "black")
leg_strokeWidth: stroke-width (default: 0.5)
leg_fillOpacity: stroke opacity (same as the layer displayed)
leg_txtcol: color of the text (default: "#363636")

Spikes

The spikes type is used to draw a map with spikes. Source, Example.

Code

bertin.draw({
  layers: [
    {
      type: "spikes",
      geojson: countries,
      values: "pop",
      k: 60,
      w: 8,
      tooltip: ["$country", "$pop", "(inh.)"],
    },
  ],
});

Parameters

geojson: a geojson (compulsory)
rewind: a boolean. If true, the geojson is rewinded for a proper display (default: false)
values

: a string corresponding to the targeted variable in the properties(compulsory)
k

: height of the highest peak (default:50)
w: width of the spikes (default:10)
fill

: fill color (default: #a31d88)
stroke

: stroke color (default: #a31d88)
strokeWidth

: stroke width (default: 0.7)
fillOpacity

: fill opacity (default: 0.3)
tooltip an array of values defining what to display within the tooltip. If you use a $, the value within the geojson is displayed.
viewof: Boolean to use this layer as an Observable view. See explanations (default: false)

Parameters of the legend

leg_x: position in x (if this value is not filled, the legend is not displayed)
leg_y: position in y (if this value is not filled, the legend is not displayed)
leg_fill: color of the circles (default: "none")
leg_stroke: stroke of the circles (default: "black")
leg_strokeWidth: stoke-width (default: 0.8)
leg_txtcol: color of the text (default: "#363636")
leg_title: title of the legend (default var_data)
leg_round: rounding (default: undefined)
leg_fontSize: title legend font size (default: 14)
leg_fontSize2: values font size (default: 10)

Ridge

The ridge type allows to produce 2.5D maps by varying the height of lines. The method takes as input polygons or multi polygons. Source Example.

Code

bertin.draw({
  layers: [
 {
      type: "ridge",
      geojson: data,
      values: "pop",
      step: 30,
      blur: 0.4,
      k: 50
    },
  ],
});

Parameters

geojson: a geojson (compulsory)
rewind: a boolean. If true, the geojson is rewinded for a proper display (default: false)
values: a string corresponding to the targeted variable in the properties
stroke

: stroke color (default: "white")
strokeWidth stroke width (default: 0.5)
fillOpacity

: fill opacity (default: 1)
strokeOpacity

: stroke opacity (default: 1)
strokeDasharray

: stroke-dasharray (default: "none")
step: Gap between the points (default: 20)
k: Height of lines (default: 100)
operator: "sum" for absolute quantitative data or "mean" for relative data (default: "mean")
geoprocessing: "intersection" (intersection between polygons and grid squares. Assignment of values in proportion to the intersected area) or "dotinpoly" (considers each grid square and assigns the value of the underlying polygon or the weighted average of intersecting polygons. ). (Default: "dotinpoly")
blur: radius of the kernel defined in d3.blur2 (default: 0.4)

Smooth

The smooth type (or heatmap or contour) is a way to produce a continuous représentations from quantitative data. The algorithm is complex. The values produced do not really make sense. Explanations with the parameters. Source, Example and methodology.

Code

bertin.draw({
  layers: [
 {
      type: "smooth",
      geojson: data,
      values: "pop",
      thresholds: 50,
      bandwidth: 25,
      colorcurve: 1,
    },
  ],
});

Parameters

geojson: a geojson (compulsory)
rewind: a boolean. If true, the geojson is rewinded for a proper display (default: false)
values: a string corresponding to the targeted variable in the properties
stroke: stroke color (default: "white")
strokeWidth stroke width (default:0.5)
strokeLinecap: stroke-linecap (default:"round")
strokeLinejoin: stroke-linejoin (default:"round")
strokeDasharray: stroke-dasharray (default:"none")
fillOpacity: fill opacity (default:1)
strokeOpacity: stroke opacity (default:1)

Contour parameters

fill: color palette. "Blues", "Greens", "Greys", "Oranges", "Purples", "Reds", "BrBG", "PRGn", "PiYG", "PuOr", "RdBu", "RdYlBu", "RdYlGn", "Spectral","Turbo","Viridis","Inferno", "Magma", "Plasma", "Cividis", "Warm", "Cool", "CubehelixDefault", "BuGn", "BuPu", "GnBu", "OrRd", "PuBuGn", "PuBu", "PuRd", "RdPu", "YlGnBu", "YlGn", "YlOrBr", "YlOrRd", "Rainbow", "Sinebow". (default: RdYlGn)
thresholds: number of classes (default: 100)
bandwidth: bandwidth (the standard deviation) of the Gaussian kernel and returns the estimate. (default: 5)
colorcurve: a value to curve the color interpolation (default: 2)
reverse: a boolean reverse the colors (default: false)
remove: number of polygons to remove (default: 0)
clip: a boolean to clip the contours with the input geojson (default: false)

By default, the smooth layer is calculated from dots or centroids. But it is possible to go through a regular grid by using theses parameters.

grid_step: Gap between the points (default:20)
grid_blur: radius of the kernel defined in d3.blur2 (default: 0)
grid_operator: "sum" for absolute quantitative data or "mean" for relative data (default: "sum". highly recommended)
grid_geoprocessing: "intersection" (intersection between polygons and grid squares. Assignment of values in proportion to the intersected area) or "dotinpoly" (considers each grid square and assigns the value of the underlying polygon or the weighted average of intersecting polygons. ). (Default: "intersection")

Thickness

On each layer, you can dynamically vary the thickness of the paths. This can be useful to make for example flow maps or discontinuity maps. Source

Code - Constant Thickness

In order for each object to have the same thickness.

bertin.draw({
  layers: [
    {
      type: "layer",
      geojson: *a geojson here*,
      strokeWidth: 3,
    }
  ]
})

Code - Linear variation

To vary the thickness proportionally to an quantitative data.

bertin.draw({
  layers: [
    {
      type: "layer",
      geojson: *a geojson here*,
      strokeWidth: {type:"linear",values:"migration"},
    }
  ]
})

Parameters

values

: a string corresponding to the targeted variable in the properties(compulsory)
k

: thicken with the largest line (default:10)
fixmax

: Max value to fix the size of the thickest line, in order to make maps comparable (default:undefined)
fixmin

: Min value to fix the size of the thinest line. If true, the value is the min data. (default:0)

Code - Discrete variation

To vary the thickness according to classes values

bertin.draw({
  layers: [
    {
      type: "layer",
      geojson: *a geojson here*,
      strokeWidth: {type:"discr",values:"migration", method: "q6"},
    }
  ]
})

Parameters

values

: a string corresponding to the targeted variable in the properties(compulsory)
k

: thicken with the largest line (default:10)
nbreaks

: Number of classes (default:5)
breaks

: Class breaks (default:null)
method

: A method of classification. "quantile", "q6", "equal", "msd", "jenks", "geometric", "headtail" or "pretty" (default: "quantile").
middle

: for msd method only. middle class or not (default:false).
sizes

: an array definig the sizes of each classes.
nbsd

: for msd method only. number of sd. (default:1)
sizes

: an array of thicknesses.

Code - Categories

To vary the thickness according to qualitative data.

bertin.draw({
  layers: [
    {
      type: "layer",
      geojson: *a geojson here*,
      strokeWidth: {type:"quali",values:"flow", categories: ["low", "medium", "high", "very high"]},
    }
  ]
})

Parameters

values

: a string corresponding to the targeted variable in the properties(compulsory)
k

: thicken with the largest line (default:10)
categories

: an array containing categories
sizes

: an array definig the sizes of each classes.
nbsd

: for msd method only. number of sd. (default:1)
sizes

: an array of thicknesses.

Parameters of the legends

leg_x

: position in x (if this value is not filled, the legend is not displayed)
leg_y

: position in y (if this value is not filled, the legend is not displayed)
leg_w

: width of the lines (default: 30)
leg_text

: text of the box (default: "leg_text")
leg_fontSize

: text font size (default: 10)
leg_fill

: color of the box (same as the layer displayed)
leg_stroke

: stroke of the box (default: "black")
leg_strokeWidth

: stroke-width (default: 0.5)
leg_fillOpacity

: stroke opacity (same as the layer displayed)
leg_txtcol

: color of the text (default: "#363636")
leg_round

: Number of digits (default: undefined)

Map components {#map-components}

Footer

The footer type allows to display text under the map. This is useful to display sources. Source.

Code

bertin.draw({
  layers: [
    {
      type: "footer",
      text: "Source: Worldbank, 2021",
      fontSize: 10,
    },
  ],
});

Parameters

text

: text to be displayed (default:"")
anchor: text anchor. start, middle, end (default:"end")
fontSize: size of the text (default:15)
fill: color of the text (default:"#9e9696")
background: background color (default: "white")
backgroundOpacity: background opacity (default: 1)

Geolines

The geolines type allows you to display geographic lines (equator, tropics, polar circles). Source.

Code

bertin.draw({
  layers: [
    {
      type: "geolines",
      stroke: "black",
      strokeWidth: [5, 3, 1],
    },
  ],
});

Parameters

For each parameter, you can set a single value for all lines are an array in that order: [equator, tropics, polar].

stroke

: stroke color (default: "#020e21")
strokeWidth: stroke width (default: [1.5, 1.2, 0.7])
strokeOpacity

: stroke opacity (default: 1)
strokeDasharray: stroke-dasharray (default: ["none", 5, 3])
strokeLinecap

: stroke-linecap (default: "butt")

Graticule

The graticule type allows you to display the latitude and longitude lines around . Source.

Code

bertin.draw({
  layers: [
    {
      type: "graticule",
      stroke: "#644580",
      step: [20, 10],
    },
  ],
});

Parameters

stroke

: stroke color (default:"white")
strokeWidth

: stroke width (default:0.8)
strokeOpacity

: stroke opacity (default:0.5)
strokeDasharray

: stroke-dasharray (default:2)
step: gap between graticules. The value can be a number or an array of two values (default: [10, 10])
spread: A value in degrees to extend the graticules beyond the geometries (default: 0)

hatch (or hatching)

The hatch type only allows to add hatchings on the whole page to make it a bit prettier. Source.

Code

bertin.draw({
  layers: [
    {
      type: "hatch",
      angle: 45,
    },
  ],
});

Parameters

stroke: stroke color (default: "#786d6c")
strokeWidth: stroke color (default: 2)
strokeOpacity: stroke-opacity (default: 45)
strokeDasharray: stroke-dasharray (default:"none")
angle: orientation of lines (default: 45)
spacing: spacing between lines (default: 8)

Inner

The inner type allows to display a strip inside the polygon. This inner area can be used to draw preet maps with a vintage style.

Code

bertin.draw({
  layers: [
    {
      type: "inner",
      thickness: 5,
      fill:"white",
      blur:4
    },
  ],
});

Parameters

thickness: a thickness in pixels (default: 7)
fill: fill color (default: "#9e9477")
fillOpacity: fill-opacity (default: 0.2)
blur: blur. feGaussianBlur stdDeviation value (default:4)

Minimap (location map)

The minimap type (or location) allows to display a location map showing the coverage of the map. Source. Example

bertin.draw({
  layers: [
    {
      type: "minimap",
      x: 50,
      y: 50,
      width:300,
      frame:{fill: "yellow", stroke: "none"}
    },
  ],
});

Parameters

x: position in x (default: 5)
y: position in y (default: 5)
width: Width (default: 200)
projection: minimap projection (default: "Equirectangular")
geojson: geometries of the map (default: null)
extent: minimap extent (default: null)
threshold: area defining the threshold between dot and polygon representation (default: 0.1)
background: an object to define the style of the background (default: {stroke: "black", strokeWidth: 1, strokeOpacity: 1, fill: "white", fillOpacity: 1})
geometries: an object to define the style of the basemap (default: {fill: "#CCC", stroke: "none", strokeWidth: 1, fillOpacity: 1, strokeOpacity: 1})
raise: an object to define the style of the highlight area (default: {fill: "red", stroke: "none", strokeWidth: 1, fillOpacity: 1, strokeOpacity: 1})
frame: an object to define the style of the frame (default: {stroke: "none", strokeWidth: 1, strokeOpacity: 1, fill: "red", fillOpacity: 0.25})
dot: an object to define the style of the dot (default: {fill: "red", r: 5, stroke: "none", strokeWidth: 1, fillOpacity: 1,strokeOpacity: 1})

Rhumbs

The rhumbs type allows to display "rhumb lines" like on old portolan charts. Source.

Code

bertin.draw({
  layers: [
    {
      type: "rhumbs",
      position: [370, 370],
      nb: 25
    },
  ],
});

Parameters

nb

: number of lines (default: 10)
position

: position of the center in x and y (default: [height / 4, width - width / 4])
stroke

: stroke color (default: "#786d6c")
strokeWidth

: stroke color (default: 2)
strokeOpacity

: stroke-opacity (default: 45)
strokeDasharray

: stroke-dasharray (default:"none")

Water lines (slow)

The waterlines type only allows to display lines spaced by a defined distance. It's just a graphic trick to make the maps look nice. Source.

Code

bertin.draw({
  layers: [
    {
      type: "waterlines",
      geojson: world,
      dist: 100,
      nb: 5
    },
  ],
});

Parameters

dist: distance between lines in pixels (default: 5)
nb: number of lines (default: 3)
precision: number of steps defining buffers. 1 = not accurate, 8 = accurate. (default: 3)
stroke: stroke. If more than 1 value is defined, a linear scale is done beetwen values (default:"#5d81ba")
strokeOpacity: stroke-opacity. If more than 1 value is defined, a linear scale is done beetwen values (default: [1, 0.1])
strokeWidth: stroke-width. If more than 1 value is defined, a linear scale is done beetwen values(default: [1.2, 0.2])
strokeDasharray: stroke-dasharray (default: "none")
strokeLinecap: stroke-linecap (default: "round")
strokeLinejoin: stroke-linejoin (default: "round")

logo

The logo type only allows allows to display a logo on the map from an url. By default, the bertin.js logo is displayed. Source Example.

Code

bertin.draw({
  layers: [
    {
      type: "logo",
      url: "http://myimage.png"
      position: "left",
    },
  ],
});

Parameters

url: a string containing an url(default: bertin logo)
position: an array of two cootdinates [x, y] or predefined positions as "left", "right" or "middle" (default: "left")
size: width of the logo. (default: 100)

Header

The header type allows to display a title above the map. Source.

Code

bertin.draw({
  layers: [
    {
      type: "header",
      text: "Title of the map",
      fontSize: 40,
    },
  ],
});

Parameters

text

: text to be displayed (default:"")
anchor: text anchor. start, middle, end (default:"middle")
fontSize: size of the text (default:20)
fill: color of the text (default:"#9e9696")
background: background color (default: "white")
backgroundOpacity: background opacity (default: 1)

Labels

The label type allows to display labels from a geojson. Source, Example.

Code

bertin.draw({
  layers: [
    {
      type: "label",
      geojson: countries,
      values: "name",
    },
  ],
});

Parameters

geojson: a geojson (compulsory)
rewind: a boolean. If true, the geojson is rewinded for a proper display (default: false)
values: a string corresponding to the targeted variable in the properties (compulsory)
fill: fill color (default: "#474342")
fontSize: font size (default: 10)
fontFamily: font family. "Pacifico","Roboto","Rubik","Ubuntu" (default: "Roboto")
textDecoration: text decoration. "none", "underline", "line-through", "overline" (default:"none")
fontWeight: font weight. "normal", "bold", "bolder", "lighter" (default: "normal")
fontStyle: font style. "normal", "italic", "oblique" (default: "normal")
opacity: opacity (default: 1)
halo: boolean to display a halo below the text (default: false)
halo_style: an array defining the halo style. [color, thickness, opacity] (default: ["white","4, 0.5)

Missing

The missing type displays any missing data when creating a map by proportional symbols. The highlight of graphical elements (in white under the symbols) allows for clear data comprehension of gaps in data. Source.

Code

bertin.draw({
  layers: [
    {
      type: "missing",
      geojson: countries,
      values: "pop"
  ]
})

Parameters

geojson: a geojson (compulsory)
rewind: a boolean. If true, the geojson is rewinded for a proper display (default: false)
values: a string corresponding to the targeted variable in the properties (compulsory)
fill: fill color (default: "white")
stroke: stroke color (default: "white")
strokeWidth: stroke width (default: 0.5)
fillOpacity: fill opacity (default: 1)

Parameters of the legend

leg_x: position in x (if this value is not filled, the legend is not displayed)
leg_y: position in y (if this value is not filled, the legend is not displayed)
leg_w: width of the box (default: 30)
leg_h: height of the box (default:20)
leg_text: text of the box (default: "leg_text")
leg_fontSize: text font size (default: 10)
leg_fill: color of the box (same as the layer displayed)
leg_stroke: stroke of the box (default: "black")
leg_strokeWidth: stroke-width (default: 0.5)
leg_fillOpacity: stroke opacity (same as the layer displayed)
leg_txtcol: color of the text (default: "#363636")

Outline

The outline type is used to display the limits of the earth area in the given projection. Source.

Code

bertin.draw({
  layers: [
    {
      type: "outline",
      fill: "#4269ad",
    },
  ],
});

Parameters

fill: fill color of the outline (default: "#add8f7")
opacity: opacity (default:1)
stroke: stroke color (default:"none")
strokeWidth: stroke width (default: 1)

Path

The path type is used to display any svg path Source Example

Code

bertin.draw({
  layers: [
    {
      type: "path",
      d: "m 99.330229,64.978319 -9.724281,-1.057429 -3.946379,8.950188 -3.94638,-8.950188 -9.72428,1.057429 5.7779,-7.89276 -5.7779,-7.892759 9.72428,1.05743 3.94638,-8.950189 3.94638,8.950189 9.72428,-1.057429 -5.777901,7.892759 z",
      fill:"blue",
      sroke: "none",
      scale: 2

    },
  ],
});

Parameters

d: string containg svg path
x: x position (default: 0)
y: y position (default: 0)
scale: scale (default: 1)
rotate: angle (defalut: 0)
style: "fit", "raw" or "repeat". "fit" allows to set the path on the top left of the document. "raw" uses the coordinates as they are. "repeat" alows to build a pattern from the path (default: "fit")
fill: fill color (default: "#add8f7")
opacity: opacity (default:1)
stroke: stroke color (default:"none")
strokeWidth: stroke width (default: 1)
strokeLinecap: stroke-linecap (default:"round")
strokeLinejoin: stroke-linejoin (default:"round")
strokeDasharray: stroke-dasharray (default:"none")

Scalebar

The scalebar type allows to display a scale bar in miles or kilometers. Source.

Code

bertin.draw({
  layers: [
    {
      type: "scalebar",
      units: "miles",
    },
  ],
});

Parameters

x: position in x (if this value is not filled, the legend is displayed on the left)
y: position in x (if this value is not filled, the legend is displayed at the bottom)
units: distance unit, miles or kilometers (default: "kilometers")

Shadow

The shadow type allows to display a shadow under a layer to give it a relief effect. Source.

Code

bertin.draw({
  layers: [
    {
      type: "shadow",
      geojson: JPN,
      dx: 5,
      dy: 5,
    },
  ],
});

Parameters

fill

: color (default: "#35383d")
dx

: shift in x (default: 3)
dy

: shift in y (default: 3)
stdDeviation: blur (default: 1.5)
opacity

: opacity (default: 0.7)

Texts

The text type simply allows you to display text anywhere on the map. Source. Example.

Code

bertin.draw({
  layers: [
    {
      type: "text",
      text: "This is my text",
      position: "bottomright",
      fontSize: 20,
      frame_stroke: "red",
      margin: 4,
    },
  ],
});

Parameters

position: position of the text. It can be an array with x,y coordinates. For example [100,200]. It can be also a string defining the position. "topleft", "top", "topright", "left", "middle", "right", "bottomleft", "bottom", "bottomright" (default: "topleft")
text: text to display. With the backticks, it is possible to display a text on several lines (default: "Your text here!")
fontSize: text size (default: 15)
fontFamily: font family. "Pacifico","Roboto","Rubik","Ubuntu" (default: "Roboto")
textDecoration: text decoration. "none", "underline", "line-through", "overline" (default:"none")
fontWeight: font weight. "normal", "bold", "bolder", "lighter" (default: "normal")
fontStyle: font style. "normal", "italic", "oblique" (default: "normal")
margin: margin around the text (default: 0)
anchor: text anchor. start, middle, end (default: "start")
fill: text color (default: "#474342")
stroke: stroke color (default: "none")
frame_fill: frame background color (default:"none")
frame_stroke: frame stroke color (default: "none")
frame_strokeWidth: thickness of the frame contour (default: 1)
frame_opacity: frame opacity (default: 1)

Mercator Tiles

The tiles type allow to display a raster basemap. Source. Example.

NB: It works only with the d3.geoMercator() projection. if tiles layer is used is the draw function, the projection is automaticaly setted to d3.geoMercator(). And you can't change it.

Code

bertin.draw({
  params: { 
            projection: d3.geoMercator(),
            extent: *a geojson*  
          },
  layers: [
    {
      type: "tiles",
      style: "worldphysical"
    },
  ],
});

Parameters

style: tile style: "openstreetmap", "opentopomap", "worldterrain", "worldimagery", "worldStreet", "worldphysical", "shadedrelief", "oceanbasemap". (default: "opentopomap"). You can alse use configurable like this:

style: {
  provider: "OpenStreetMap contributors", 
  url: (x, y, z) => `https://tile.openstreetmap.org/${z}/${x}/${y}.png`,
   }

zoomDelta: zoom offset. See explanations here (default:0)
tileSize: tile size. See explanations here (default:512)
opacity: tile opacity (default:1) -clip: a geojson to clip the image
source: position of the text. It can be an array with x,y coordinates. For example [100,200]. It can be also a string defining the position. "topleft", "top", "topright", "left", "middle", "right", "bottomleft", "bottom", "bottomright" (default: "topleft")
increasetilesize: a value to slightly increase the size of the tiles solve the problem of gap between the tiles with chromium (deafault: 1)

Tissot's indicatrix

The tissot type aims to draw Tissot circles to visualize the deformations due to the projection Source.

Code

bertin.draw({
  layers: [
    {
      type: "tissot",
      step: 20
    },
  ],
});

Parameters

step

: step between circles
fill

: fill (default: "#d91848")
fillOpacity

: fill-opacity (default: 0.5)
stroke

: stroke (default: "#d91848")
strokeOpacity

: stroke-opacity (default: 0.6)
strokeWidth

: stroke-width (default: 1.5)

Custom Layer {#custom-layer}

The custom type (or function type) allows you to provide your own render function to create custom layer. [Example]

Code

bertin.draw({
  layers: [
    {
      type: "custom",
      render: function (svg, map) {
        svg
          .append("g")
          .append("rect")
          .attr("x", map.width / 2)
          .attr("y", map.height / 2)
          .attr("height", 100)
          .attr("width", 200)
          .style("fill", "red");
      }
    },
    { geojson: world, fill: "white" },
    { type: "graticule" },
    { type: "outline" }
  ]
})

Or with an external function

function drawRectangle(svg, map, options) {
  const { fill, stroke, strokeWidth } = options; // Will have all options (parameters) set in the curret layer object, right?
  svg
    .append("g")
    .append("rect")
    .attr("x", map.width / 2)
    .attr("y", map.height / 2)
    .attr("height", 100)
    .attr("width", 200)
    .style("fill", fill)
    .style("stroke", stroke)
    .style("stroke-width", strokeWidth);
}

then:

bertin.draw({
  params: { extent: world, width: 1000 },
  layers: [
    {
      type: "function",
      render: drawRectangle,
      fill: "red",
      stroke: "blue",
      strokeWidth: 10
    },
    { geojson: world, fill: "white" },
    { type: "graticule" },
    { type: "outline" }
  ]
})

with

map.width: the width of the map map.height: the height of the map
map.projection: the projection of the map map.clipid: the unique id of the map

Geojson properties selections {#geojson-properties-selections}

properties.add

properties.add allows to add a new field in the att ribute table. This function return a new object and do not modify the initial object. Example. Code.

Code

bertin.properties.add({
    geojson: world, 
    field: "gdppc", 
    expression: "gdp/pop*1000" 
})

Parameters

geojson: a geojson
field: new colname (string)
expression: a string containing an expression

properties.filter

properties.filter allows to filter a geojson from its attribute table.This function return a new object and do not modify the initial object. Example. Code.

Code

bertin.properties.filter({
    x: world,
    expression: "pop2022 >= 100000" 
})

Parameters

geojson: a geojson
expression: a string containing an expression

properties.head

properties.head allows to get the n top values from a given field.This function return a new object and do not modify the initial object. Example. Code.

Code

bertin.properties.head({
    geojson: world,
    field: "gdp",
    nb: 5
})

Parameters

geojson: a geojson
field: a string containing an colname
nb: number of features to get (default:10)

properties.keep

properties.keep allows to select one or several columns to keep in the attribute table. All other columns are deleted. This function return a new object and do not modify the initial object. Example. Code.

Code

bertin.properties.keep({
    geojson: world,
    field: ["ISO3", "pop2020"] 
})

Parameters

geojson: a geojson
field: fields to keep (string or array of strings)

properties.remove

properties.remove allows to remove one or several columns in the attribute table. This function return a new object and do not modify the initial object. Example. Code.

Code

bertin.properties.remove({
    geojson: world,
    field: ["tmp", "FID"] 
})

Parameters

geojson: a geojson
field: fields to remove (string or array of strings)

properties.subset

properties.subset allows to remove one or several columns in the attribute table. This function return a new object and do not modify the initial object. Example. Code.

Code

bertin.properties.subset({
    geojson: world,
    field: "ISO3",
    selection:   ["USA", "CAN", "MEX"],
    inverse: false
})

Parameters

geojson: a geojson
field: fields to remove (string or array of strings)
selection: values to be kept. In the example above, North american countries
inverse: default: false. If true, all countries except USA, CAN and MEX are kept

properties.table

properties.subset allows to get a geojson attribute table Example. Code.

Code

bertin.properties.table(*a geojson*)

properties.head

properties.tail allows to get the n bottom values from a given field. This function return a new object and do not modify the initial object. Example. Code.

Code

bertin.properties.tail({
    geojson: world,
    field: "gdp",
    nb: 5
})

Parameters

geojson: a geojson
field: a string containing an colname
nb: number of features to get (default:10)

Other functions {#other-functions}

borders

borders is a function that extract borders from polygons, with ids. Source

Code

bertin.borders({geojson: world, id: "iso3", values: "population", type = "rel"})

Parameters

geojson: a geojson
id: id codes
values: values
type: type of discontinuities calculated: rel(relative), abs(absolute) (default:"rel")

bbox

bbox computes a geojson object form an array defining an extent in latitude and longitude.

Code

bertin.bbox([
  [112, -43],
  [153, -9],
]);

Quickdraw

quickdraw function displays one or more layers directly and easily. Source, Example.

Code

bertin.quickdraw(geojson);

bertin.quickdraw(geojson, 1000, 7);

Parameters

param 1 : a geojson (compulsory)
param 2 : width
param 3 : margin

Match

match() is a function to evaluate the quality of a join between the data and the background map. It returns a chart. Source, Example.

Code

let testjoin = bertin.match(countries, "ISO3_CODE", maddison, "countrycode");

.matched returns an array containing matched ids

testjoin.matched;

.matched_data returns an array containing matched data ids

testjoin.matched_data;

.unmatched_data returns an array containing unmatched data ids

testjoin.unmatched_data;

.unmatched_geom returns an array containing unmatched geom ids

testjoin.unmatched_geom;

Parameters

param 1 : a geojson (compulsory)
param 2 : a string corresponding to the identifier of the features in the properties (compulsory)
param 3 : a json (compulsory)
param 4 : a string corresponding to the identifier of the features (compulsory)

Merge

merge is a function to join a geojson and a data file. This is the first step in the mapping process. Source, Example.

Code

const data = bertin.merge(
  countries,
  "ISO3_CODE",
  maddison,
  "countrycode",
  true
);

Parameters

param 1 : a geojson (compulsory)
param 2 : a string corresponding to the identifier of the features in the properties (compulsory)
param 3 : a json (compulsory)
param 4 : a string corresponding to the identifier of the features (compulsory)
param 5 : a boolean. If true, all geometries will be kept. If false, only matched data are kept (default: true)

links

links is a function that create links from geometries (polygons or points) and a data file (i,j,fij). Source Example.

Code

bertin.links({
  geojson: world,
  geojson_id: "ISO3",
  data: migr2019,
  data_i: "i",
  data_j: "j",
});

Parameters

geojson: a geojson
geojson_id: id of the geojson
data: inj,fij data
data_i: i id
data_j: j id
planar: a boolean. Set true if coordinates are already projected (default: false)

subgeo

Depreciated. See properties.subset/

table2geo

table2geo function converts a data table with lat/lon fields or a coords field to a geojson. Source, Example.

Code

bertin.table2geo(cities, "lat", "lng");

Or

bertin.table2geo(cities, "coords");

Parameters

param 1 : a geojson (compulsory)
param 2 : latitude (or coords)
param 3 : longitude

Info

After creating a map, you can have access to the map info (width, total height, map height, footer height, header height, projection).

Code

mymap = bertin.draw({
  params: {
    projection: d3.geoBertin1953(),
    width: 750,
  },
  layers: [...]
})

then

mymap.info

Observable viewof

Within Observable, you can use bertin maps as Inputs by using viewof. In Observable, a view is a user interface element that directly controls a value in the notebook. See explanations here: https://observablehq.com/@observablehq/views.

In bertin, you can define which layer(s) are used by specifying the viewof parameter at the layer level. It works for simple, bubble, square, dotcartogram, mushroom, regularbubble, regularsquare, regulargrid and spikes layer.

Code

viewof map = bertin.draw({
  layers: [
    {
      type: "bubble",
      geojson: *a geojson*,
      values:"pop",
      viewof: true
    },
    {
      type: "layer",
      geojson: *another geojson*,
      viewof: false
    }
  ]
})

Then

map

If you do not specify any particular layer, map will return the coordinates of the mouse cursor.

Update function {#update-function}

Since version 1.7 of bertin, an update function function is available. It allows you to modify specific attributes and styles without having to redraw the entire map. Not everything can be modified. Only the attributes underlined in the documentation are.

To use it, you must first create a map with the draw function add an identifier to each layer.

map = bertin.draw({
  layers: [
    {
      id: "mylayerid",
      geojson: data,
      fill: "red"
    }
  ]
})

Then you can apply the update function linked to the map to modify the styles and attributes. example

Code

map.update({
  id: "mylayerid",
  attr: "fill",
  value: "blue",
  duration: 1000
})

Parameters

id: the layer id
attr: the attribute to change
value: The new value to give to the attribute
delay: The time before making the change
duration: The time of transition
legend: In some cases, changing the attribute requires changing the title of the legend. You can do this via the legend parameter.

Example 1

NB: The update function will also allow you to show and hide the layers of your map. See an example here.

Bonus: an overview of available layer types

What's available in the bertin javascript library? What types of maps can be made? Thanks to this cheat sheet, you have an overview of the "types" available in the library. All these thumbnails are generated for real with the bertin@1.5.9 in this notebook.

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LICENSE		LICENSE
README.md		README.md
TODO.md		TODO.md
package-lock.json		package-lock.json
package.json		package.json
rollup.config.js		rollup.config.js

License

riatelab/bertin

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Cheat Sheet

Who is Bertin? {#who-is-bertin}

Installation {#installation}

In browser

In Observable

In Quarto

Usage {#usage}

In browser

In Observable Notebook

Drawing a map {#drawing-a-map}

Global parameters

Code

Parameters

Map types {#map-types}

Simple layer

Code

Parameters

Choropleth

Code

Parameters

Typology

Code

Parameters

Bubble

Code

Parameters

Square

Code

Parameters

Regular Bubble

Code

Parameters

Regular Square

Code

Parameters

Regular grid

Code

Parameters

Stock and ratio

Code

Stock and typo

Code

Dorling cartogram

Code

Dot cartogram

Code

Parameters

Mushroom

Code

Parameters

Dot Density

Code

Parameters

Spikes

Code

Parameters

Ridge

Code

Parameters

Smooth

Code

Parameters

Thickness

Code - Constant Thickness

Code - Linear variation

Parameters

Code - Discrete variation

Parameters

Code - Categories

Parameters

Parameters of the legends

Map components {#map-components}

Footer

Code