supplement_animating_maps.ipynb

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        "id": "63a4a6b3-3860-4ec1-b8a1-f781d536e400"
      },
      "source": [
        "### Creating Animated Maps"
      ]
    },
    {
      "cell_type": "markdown",
      "id": "31062a14-f21f-4ff6-9b96-a5bc5f5efec7",
      "metadata": {
        "id": "31062a14-f21f-4ff6-9b96-a5bc5f5efec7"
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      "source": [
        "We take the dataset for 2017 solar eclipse and animate the path of the solar eclipse.\n",
        "\n",
        "<img src='https://courses.spatialthoughts.com/images/python_dataviz/eclipse_animation.gif' width=600/>"
      ]
    },
    {
      "cell_type": "markdown",
      "source": [
        "#### Setup and Data Download\n",
        "\n",
        "The following blocks of code will install the required packages and download the datasets to your Colab environment."
      ],
      "metadata": {
        "id": "tOzdEMTKdEK3"
      },
      "id": "tOzdEMTKdEK3"
    },
    {
      "cell_type": "code",
      "source": [
        "%%capture\n",
        "if 'google.colab' in str(get_ipython()):\n",
        "  !pip install contextily"
      ],
      "metadata": {
        "id": "H3xtRd2DdH5Q"
      },
      "execution_count": null,
      "outputs": [],
      "id": "H3xtRd2DdH5Q"
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    {
      "cell_type": "code",
      "execution_count": null,
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        "id": "2hMR9wgfyq-4"
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      "outputs": [],
      "source": [
        "import requests\n",
        "import contextily as cx\n",
        "import geopandas as gpd\n",
        "import os\n",
        "import matplotlib.pyplot as plt\n",
        "from matplotlib.animation import FuncAnimation, PillowWriter\n",
        "import shapely"
      ],
      "id": "2hMR9wgfyq-4"
    },
    {
      "cell_type": "code",
      "source": [
        "data_folder = 'data'\n",
        "output_folder = 'output'\n",
        "\n",
        "if not os.path.exists(data_folder):\n",
        "    os.mkdir(data_folder)\n",
        "if not os.path.exists(output_folder):\n",
        "    os.mkdir(output_folder)"
      ],
      "metadata": {
        "id": "x7g96whjdjZ1"
      },
      "execution_count": null,
      "outputs": [],
      "id": "x7g96whjdjZ1"
    },
    {
      "cell_type": "code",
      "source": [
        "def download(url):\n",
        "    filename = os.path.join(data_folder, os.path.basename(url))\n",
        "    if not os.path.exists(filename):\n",
        "      with requests.get(url, stream=True, allow_redirects=True) as r:\n",
        "          with open(filename, 'wb') as f:\n",
        "              for chunk in r.iter_content(chunk_size=8192):\n",
        "                  f.write(chunk)\n",
        "      print('Downloaded', filename)"
      ],
      "metadata": {
        "id": "3C-a1309_DtE"
      },
      "id": "3C-a1309_DtE",
      "execution_count": null,
      "outputs": []
    },
    {
      "cell_type": "code",
      "source": [
        "path_shapefile = 'upath17'\n",
        "umbra_shapefile = 'umbra17'\n",
        "shapefile_exts = ['.shp', '.shx', '.dbf', '.prj']\n",
        "data_url = 'https://github.com/spatialthoughts/python-dataviz-web/releases/' \\\n",
        "  'download/eclipse/'\n",
        "\n",
        "for shapefile in [path_shapefile, umbra_shapefile]:\n",
        "  for ext in shapefile_exts:\n",
        "    url = data_url + shapefile + ext\n",
        "    download(url)"
      ],
      "metadata": {
        "id": "kXOsjbAcdlf7"
      },
      "execution_count": null,
      "outputs": [],
      "id": "kXOsjbAcdlf7"
    },
    {
      "cell_type": "markdown",
      "source": [
        "#### Data Pre-Processing"
      ],
      "metadata": {
        "id": "bCLVZLHHeFOS"
      },
      "id": "bCLVZLHHeFOS"
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "id": "_L4L2hY2y4y5"
      },
      "outputs": [],
      "source": [
        "path_shapefile_path = os.path.join(data_folder, path_shapefile + '.shp')\n",
        "path_gdf = gpd.read_file(path_shapefile_path)"
      ],
      "id": "_L4L2hY2y4y5"
    },
    {
      "cell_type": "code",
      "source": [
        "umbra_shapefile_path = os.path.join(data_folder, umbra_shapefile + '.shp')\n",
        "umbra_gdf = gpd.read_file(umbra_shapefile_path)"
      ],
      "metadata": {
        "id": "FGNd4SrVqYlt"
      },
      "execution_count": null,
      "outputs": [],
      "id": "FGNd4SrVqYlt"
    },
    {
      "cell_type": "code",
      "execution_count": 16,
      "id": "92dc4eca-0e06-49f7-ba36-20325dca9808",
      "metadata": {
        "id": "92dc4eca-0e06-49f7-ba36-20325dca9808"
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      "outputs": [],
      "source": [
        "crs = 'EPSG:9311'\n",
        "\n",
        "path_reprojected = path_gdf.to_crs(crs)\n",
        "umbra_reprojected = umbra_gdf.to_crs(crs)\n",
        "\n",
        "# Use the bounding box coordinates for continental us\n",
        "usa = shapely.geometry.box(-125, 24, -66, 49)\n",
        "usa_gdf = gpd.GeoDataFrame(geometry=[usa], crs='EPSG:4326')\n",
        "usa_gdf_reprojected = usa_gdf.to_crs(crs)\n",
        "bounds = usa_gdf_reprojected.total_bounds"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": 17,
      "id": "8d2a33a7-9766-4aa2-8c0f-b80b01db7a1b",
      "metadata": {
        "id": "8d2a33a7-9766-4aa2-8c0f-b80b01db7a1b"
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      "outputs": [],
      "source": [
        "path_boundary = path_reprojected.geometry.unary_union\n",
        "umbra_subset = umbra_reprojected[umbra_reprojected.geometry.intersects(path_boundary)]"
      ]
    },
    {
      "cell_type": "markdown",
      "source": [
        "#### Creating Animation\n",
        "\n",
        "We use Matplotlibs `FuncAnimation` function from the `animation` module to create an animation with each frame showing the position of the umbra through the solar eclipse.\n",
        "\n",
        "Reference: [`matplotlib.animation.FuncAnimation`](https://matplotlib.org/stable/api/_as_gen/matplotlib.animation.FuncAnimation.html)"
      ],
      "metadata": {
        "id": "8L718mTCkQV-"
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      "id": "8L718mTCkQV-"
    },
    {
      "cell_type": "code",
      "execution_count": 28,
      "id": "98eefa76-421e-4fab-a547-097e2427ea6a",
      "metadata": {
        "id": "98eefa76-421e-4fab-a547-097e2427ea6a"
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      "outputs": [],
      "source": [
        "fig, ax = plt.subplots(1, 1)\n",
        "fig.set_size_inches(15,7)\n",
        "\n",
        "def animate(i):\n",
        "    ax.clear()\n",
        "    # Set the bounds\n",
        "    ax.set_xlim(bounds[0], bounds[2])\n",
        "    ax.set_ylim(bounds[1], bounds[3])\n",
        "    # Get the point from the points list at index i\n",
        "    umbra_filtered = umbra_subset.iloc[i:i+1]\n",
        "\n",
        "    path_reprojected.plot(\n",
        "      ax=ax,\n",
        "      facecolor='#969696',\n",
        "      edgecolor='none',\n",
        "      alpha=0.5)\n",
        "    umbra_filtered.plot(\n",
        "      ax=ax,\n",
        "      facecolor='#252525',\n",
        "      edgecolor='none')\n",
        "    cx.add_basemap(ax,\n",
        "      crs=path_reprojected.crs,\n",
        "      source=cx.providers.OpenTopoMap,\n",
        "      zoom=5)\n",
        "    ax.set_axis_off()\n",
        "    props = dict(boxstyle='round', facecolor='wheat', alpha=0.5)\n",
        "    time = umbra_filtered.iloc[0].Time\n",
        "    text = 'Time: {} UTC'.format(time)\n",
        "    ax.text(0.05, 0.20, text, transform=ax.transAxes, fontsize=16,\n",
        "            verticalalignment='top', bbox=props)\n",
        "    ax.set_title('2017 Total Solar Eclipse Path', size = 18)\n",
        "\n",
        "ani = FuncAnimation(fig, animate, frames=len(umbra_subset),\n",
        "                    interval=500, repeat=True, cache_frame_data=True)\n",
        "plt.close()"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": 29,
      "id": "6bed89a9-1ac7-4e24-8a6c-46eff2901201",
      "metadata": {
        "id": "6bed89a9-1ac7-4e24-8a6c-46eff2901201"
      },
      "outputs": [],
      "source": [
        "output_folder = 'output'\n",
        "output_path = os.path.join(output_folder, 'solar_eclipse.gif')\n",
        "\n",
        "ani.save(output_path, writer=PillowWriter(fps=5))\n",
        "plt.close()"
      ]
    }
  ],
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