Add Trend indicator

[MarcSkovMadsen]

The Trend indicator enables the user to display a Dashboard KPI Card with

• Title: The name or a short title
• Value: Primary Value to display. For example an absolute value.
• Value_change: A secondary value. For example a percentage change.
• Plot: A plot. One of line", "step", "area", "bar

The card can be layout out as

• a column (text and plot on top of each other) or
• a row (text and plot after each other)

You can run the streaming test example below via

 python -m panel serve 'panel\tests\widgets\test_stats_plot_card.py' --dev --show

Must do

• support row layout
• document via notebook
• Identify and fix small responsive, resize quirks.
• verify implementation is efficient, i.e. can stream to 30 of these widgets every 500ms without memory or performance problems.
• Make sure all properties are connected as they should.
• Make it customizable whether y-axis whether contains 0.

Nice to do

• Support card description to provide more info and context of the card. Maybe shown as tooltip or via click on card.
• Add tooltip to plot if it makes sense for streaming.
• change text size/ layout calculations. Right now the text and plot uses 50% of the available height or width each. This sometimes leaves a lot of empty space in the text div.

[codecov]

Codecov Report

Merging #1895 (86db0c9) into master (c8b99f5) will increase coverage by 0.24%.
The diff coverage is 87.83%.

@@            Coverage Diff             @@
##           master    #1895      +/-   ##
==========================================
+ Coverage   84.58%   84.83%   +0.24%     
==========================================
  Files         164      166       +2     
  Lines       19821    19987     +166     
==========================================
+ Hits        16766    16956     +190     
+ Misses       3055     3031      -24     

Impacted Files	Coverage Δ
panel/widgets/__init__.py	100.00% <ø> (ø)
panel/reactive.py	74.44% <43.47%> (+3.34%)	⬆️
panel/tests/widgets/test_trend_indicator.py	76.92% <76.92%> (ø)
panel/widgets/indicators.py	94.83% <98.36%> (+0.75%)	⬆️
panel/models/__init__.py	100.00% <100.00%> (ø)
panel/models/trend.py	100.00% <100.00%> (ø)
panel/tests/widgets/test_tables.py	99.23% <100.00%> (+0.06%)	⬆️
panel/widgets/tables.py	83.80% <100.00%> (+0.47%)	⬆️
... and 5 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update c8b99f5...86db0c9. Read the comment docs.

[MarcSkovMadsen]

Additional Context

There is a video here https://discourse.holoviz.org/t/statsplotcard-pr/1689

After having studied the different "stats cards" out there I would say there are 3 archetypes

• StatsTextCard: Text Only
• StatsProgressCard: Text and a Progress Indicator
• StatsPlotCard: Text and Plot

They can the be layed out either in a column or row format.

[MarcSkovMadsen]

One question is also if you @philippjfr would you rather merge in the responsize text and stackline plot as individual indicators and let the user compose it into the card he/ she needs?

[MarcSkovMadsen]

I've added an indicator of the change

[MarcSkovMadsen]

Right now the values I stream are strings because I don't know how the user would like to round, format and add units. That is flexible but also puts more work on the user. Is that how the api should be @philippjfr ?

[MarcSkovMadsen]

I have implemented the row layout

[jbednar]

This looks really great; thanks @MarcSkovMadsen !

[philippjfr]

@jbednar Any opinions on naming this component?

[jbednar]

KPI? KPIPlot? KPICard? MetricCard? StatSummary? Too many possible names to pick just one! :-)

[philippjfr]

Tbh now looking at this I think I am now consider whether it wouldn't be better split this into distinct indicators for the value and change text and the plot.

[jbednar]

Having them be separate is good, since each makes sense on its own, but having it be easy to instantiate as a complete unit is also convenient.

[jlstevens]

In the recent HoloViz meeting I think we discussed ideas for better names than StatsPlotCard. If I remember right, I suggest something along the lines of Trend...I think the last suggestion was TrendIndicator.

I suppose my only problem with that is that other indicators don't have Indicator in their names:

Which might suggest it should simply be Trend?

[jbednar]

Hmm. Dial, Gauge, and Spinner all convey "indicator" inherently, so they aren't comparable to something like Trend which denotes the underlying numerical quantities. Number and Progress are similarly about the underlying quantity, yet somehow they seem more able to be used as indicators without stating that they are so, while Trend for me begs to have some qualifier that conveys indicator directly, e.g. TrendView or TrendDisplay or Trendline or Trendgraph or TrendStats or TrendSummary or TrendIndicator.

[jlstevens]

I quite like TrendStats.

[jbednar]

If we want to be cute, Trendicator. :-)

[philippjfr]

Performance indeed pretty decent:

[philippjfr]

I agree with the problem with TrendIndicator vs the simpler names for all the others. TrendStats I don't like much because it's really not doing much "stats" apart from displaying the change.