Truncate data refresh percent change report to 3 digits after the decimal

[AetherUnbound]

Description

PR WordPress/openverse-catalog#636 added a count difference reporting message after the data refresh has been run. Part of this count is the percent change, which is given as a float. The difficulty with printing a straight float is that the numbers after the decimal can vary wildly. Here are a few examples:

Record count difference for audio: 174,290 → 817,198
Change: +642,908 (+368.8725687073269% Δ)

Record count difference for image: 563,561,088 → 564,775,616
Change: +1,214,528 (+0.21550955625949816% Δ)

Record count difference for image: 579,553,984 → 579,554,880
Change: +896 (+0.0001546016462204149% Δ)

We have a wide range of potential digits (in the hundreds to hundredths of a percent) and it can be hard to capture the level of information we would like for all cases. I think it would be best for us to have 3 significant digits after the decimal or closest zero, rounded up. This would mean for the above three cases the output would be:

• 368.8725687073269 -> 368.873
• 0.21550955625949816 -> 0.216
• 0.0001546016462204149 -> 0.000155

Alternatives

Leave as is, or do some basic string truncation which could leave us with values like 0.000%.

Implementation

• 🙋 I would be interested in implementing this feature.

[ozgvr]

Hello, I've worked on this issue and written a function to truncate changes to 3 significant digits after the decimal and produces output exactly as the examples given.
But for very long decimals like 0.000001432153 the result gets rounded like 0.000001. Is this acceptable?

[AetherUnbound]

That is more than acceptable in my opinion! Would you like to contribute the code? I can assign this issue to you if so 😄

[mattfergoda]

I'll work on this one!