Python >> matplotlib: Get the number of lines on a current plot?

Question

Is there a way to get the number of lines currently on a matplotlib plot? I find myself setting colors in a colormap using a counter and multiplier to step through the color values--which seems rather un-pythonic.

Answer 1

All the Line2D objects in an axes are stored into a list

ax.lines  

If you use only simple line plots, the lenght of the above list is enough.

If you use plt.errorbar the situation is a bit more complicated, as it creates multiple Line2D objects (central lines, vertical and horizontal error bars and their caps).

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If you want to automatise the colours to assign to lines you can create a cycle like this

import itertools as it
colors = it.cycle(list of colors)

and then call the next color with colors.next() and restart from the first after it gets to the last