add legend.labelcolor "argument" to mplstyle stylesheet

[luke-m-olson]

A useful argument, labelcolor, was introduced in version 3.3.0 for the textual labels in legends. This allows users to color these labels with the same color as the underlying line/marker, which in turn, allows user to remove the line/marker handle/icon in favor of the colored text label.

In settings where figures are produced in a very standardized manner and that manner requires the color of the legend labels standing in for the line/marker colors of the figure, a more compact representation, the requested feature would reduce coding burden for individuals, and more importantly reduce the burden among collaborators.

Proposed Solution

A logical extension of this great addition to plt.legend would be to (if possible) include the labelcolor option/argument in the matplotlib style sheet. Allowing legend.labelcolor: linecolor along with the various other options available to labelcolor in plt.legend() into the stylesheet could reduce some coding overhead and coordination issues where legends of this type (label color standing in as line/marker) are needed, especially in teams.

Additional context and prior art

[tacaswell]

To implement this we would have to add an rcparam for legend.labelcolor (as that is the machinery that the style files feed into). A recent example of adding a new rcparams is: #17022 . The work is to:

• add the validation code for the new value
• add the default value to the matplotlbrc template
• add the checking of the rcparam at the correct place in the code
• document the new feature

Would you like to take a shot at implementing this @luke-m-olson ?

[Carloscerq]

Hi, I am a beginner in the open-source world, can I try it?

[timhoffm]

Go for it.

[tacaswell]

Closed by #20084