Embedding Formatted Numbers from 'vars' Variable in Legend Text

[kaijk]

I see from here that only x, y and customdata: variables can be used in %{<variable>:.1f} for numeric formatting.

I have a barpolar graph with no x, or y. I want to set the name that shows in the legend to a vars variable. Here is how it seems most obvious, (notwithstanding the x, y, customdata restrictions above):

name: "$ex 'Bearing ' + vars.windDirections.slice(-1) + '°, ' + %{vars.windSpeeds.slice(-1):.1f} + ' MPH'"

It doesn't work, complaining about the % sign being unexpected.

This works however showing default precision:

name: "$ex 'Bearing ' + vars.windDirections.slice(-1) + '°, ' + vars.windSpeeds.slice(-1) + ' MPH'"

I've tried using customdata with no success. It typically fails with a missing : after property id error.

Do I need to get vars.windSpeeds into customdata, somehow? I tried mapping the data onto x

x: $ex vars.windSpeeds

and then using %{x:.1f} in my name: assignment, but that didn't work either.

[dbuezas]

Use vars.windSpeeds.slice(-1).toFixed(1)

[kaijk]

This construct returns an error that, quote: vars.windSpeeds.slice(...).toFixed is not a function. But, it led me to find that

Math.round(vars.windSpeeds.slice(-1) * 1e1) / 1e1

does work for 1 decimal precision, 1e2 / 1e2 for 2 decimals, etc.

Thank you for the direction to the JS library!

[dbuezas]

Oh, it's probably a string then. You'd have to cast it to a number before using toFixed.
parseFloat(vars.windSpeeds.slice(-1)).toFixed(1)

What you did is equivalent so the best solution is the one you like the most :)