CODEWITHSUNDEEP
pythonmatplotlib
C_Z_
C_Z_

Reputation: 7796

Multiple colors for one PathPatch

Is there any way for me to have multiple colors on one matplotlib PathPatch? I have the following code and I want to, for instance, give each "segment" its own color (i.e. the segment from 0,0 to 0,1 can be red, from 0,1 to 2, 2 can be orange, from 4,3 to 5,3 can be yellow). I would like to do this without using Collections and just using the PathPatch

import matplotlib as mpl
import matplotlib.pyplot as plt

fig2, ax2 = plt.subplots()


verts = [(0,0), (0,1), (2,2), (4,3), (5,3)]
codes = [1,2,2,1,2]

pat = mpl.patches.PathPatch(mpl.patches.Path(verts, codes), fill=False, linewidth=2, edgecolor="red")
ax2.add_patch(pat)
ax2.set_xlim(-2, 6)
ax2.set_ylim(-2, 6)

Upvotes: 2

Views: 509

Answers (1)

Schorsch
Schorsch

Reputation: 7905

I haven't found a way of assigning an individual color to the segments of a mpl.patches.Path - and from the documentation, that does not appear to be possible (Path does not take any arguments related to its color/linewidth/etc.)

However - and as you state in your question - one can use a PathCollection to combine individual PathPatches of different colors.
The important argument is match_original=True.
For others in a similar situation, here is an example: 

import matplotlib as mpl
import matplotlib.pyplot as plt

fig2, ax2 = plt.subplots()


verts = [(0,0), (0,1), (2,2), (4,3), (5,3)]
codes = [[1,2],[1,2],[1,1],[1,2],[1,2]]

colors = ['red', 'orange', 'black', 'yellow']

pat = [mpl.patches.PathPatch(mpl.patches.Path(verts[i:i+2], codes[i]), fill=False, \ 
                      linewidth=2, edgecolor=colors[i]) for i in range(len(verts)-1)]

collection = mpl.collections.PatchCollection(pat, match_original=True)
ax2.add_collection(collection)

ax2.set_xlim(-2, 6)
ax2.set_ylim(-2, 6)

plt.show()

Things to note:

  • codes now became a list of lists to identify each section individually
  • colors is a list of strings with color identifiers. If you want to utilize a colormap, have a look at this answer
  • The individual patches are stored in a list, pat, the looping is done in place
  • All the patches in pat are assembled using collections.PatchCollection - here, the important argument is match_original=True, otherwise all lines will be the default black with a default line thickness

The above example produces this output:

example

Upvotes: 4

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