🎉 (grapher) round to significant figures / TAS-537

[sophiamersmann]

Adds support for rounding to significant numbers, resolves #1851

Summary

• Adds variable.display.roundingMode and variable.display.numSignificantFigures
  • The roundingMode is one of decimalPlaces or significantFigures (with decimalPlaces being the default)
  • If the roundingMode is decimalPlaces, we look at numDecimalPlaces; if the roundingMode is significantFigures, we look at numSignificantFigures
• Rounding to significant figures relies on d3's r mode ("decimal notation, rounded to significant digits"); when rounding to sig figs, trailing zeroes are always shown
• In essence, values rounded to sig figs appear everywhere expect for the table, where we use fixed-point notation

Details

• Sig fig rounded values appear in all tooltips
  • If they do, the tooltip displays a note that says "Values are rounded to X significant figures" or "Values are rounded to X or Y significant figures" (if the tooltip displays values that are rounded to different numbers of sig figs)
• Sig fig rounded values appear in the chart area; this includes:
  • Discrete bar charts
  • Stacked discrete bar charts
  • Slope charts
  • Scatter plots (value labels are used in time scatters when scatterPointLabelStrategy is set to x or y)
• Sig figs appear in the entity selector for consistency
• Sig figs don't appear in the data table, here we always use fixed-point notation (note that numDecimalPlaces is respected here)

Caveats

• Discrete bar charts and slope charts don't have tooltips, which means that we don't currently mention anywhere that we use significance rounding

Testing

• Staging site
• Observable notebook

To do

• Let Mojmir know that you added variable.display.roundingMode and variable.display.numSignificantFigures

[sophiamersmann]

• 🎉 (grapher) round to significant figures / TAS-537 #3709 👈
• master

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[notion-workspace]

Add rounding mode to variable display

[owidbot]

Quick links (staging server):

Site	Admin	Wizard

Login: ssh owid@staging-site-add-rounding-mode

• Site-screenshots: https://github.com/owid/site-screenshots/compare/add-rounding-mode
• SVG tester: https://github.com/owid/owid-grapher-svgs/compare/add-rounding-mode

SVG tester:

Number of differences (default views): 0 ✅
Number of differences (all views): 0 ✅

Edited: 2024-06-14 08:56:02 UTC
Execution time: 1.16 seconds

[danyx23]

Very nice work! I had a couple of minor comments but nothing major. I didn't look in too much detail at the rendering code for the different charts but played a little with it and it all looks good.

[sophiamersmann]

Thank you for the review! Being able to type 1_000_000 is neat 🙌🏻