Manual Contour#

Example of displaying your own contour lines and polygons using ContourSet.

import matplotlib.pyplot as plt
from matplotlib.contour import ContourSet
import matplotlib.cm as cm

Contour lines for each level are a list/tuple of polygons.

lines0 = [[[0, 0], [0, 4]]]
lines1 = [[[2, 0], [1, 2], [1, 3]]]
lines2 = [[[3, 0], [3, 2]], [[3, 3], [3, 4]]]  # Note two lines.

Filled contours between two levels are also a list/tuple of polygons. Points can be ordered clockwise or anticlockwise.

filled01 = [[[0, 0], [0, 4], [1, 3], [1, 2], [2, 0]]]
filled12 = [[[2, 0], [3, 0], [3, 2], [1, 3], [1, 2]],   # Note two polygons.
            [[1, 4], [3, 4], [3, 3]]]
fig, ax = plt.subplots()

# Filled contours using filled=True.
cs = ContourSet(ax, [0, 1, 2], [filled01, filled12], filled=True, cmap=cm.bone)
cbar = fig.colorbar(cs)

# Contour lines (non-filled).
lines = ContourSet(
    ax, [0, 1, 2], [lines0, lines1, lines2], cmap=cm.cool, linewidths=3)
cbar.add_lines(lines)

ax.set(xlim=(-0.5, 3.5), ylim=(-0.5, 4.5),
       title='User-specified contours')
User-specified contours

Out:

[(-0.5, 3.5), (-0.5, 4.5), Text(0.5, 1.0, 'User-specified contours')]

Multiple filled contour lines can be specified in a single list of polygon vertices along with a list of vertex kinds (code types) as described in the Path class. This is particularly useful for polygons with holes. Here a code type of 1 is a MOVETO, and 2 is a LINETO.

fig, ax = plt.subplots()
filled01 = [[[0, 0], [3, 0], [3, 3], [0, 3], [1, 1], [1, 2], [2, 2], [2, 1]]]
kinds01 = [[1, 2, 2, 2, 1, 2, 2, 2]]
cs = ContourSet(ax, [0, 1], [filled01], [kinds01], filled=True)
cbar = fig.colorbar(cs)

ax.set(xlim=(-0.5, 3.5), ylim=(-0.5, 3.5),
       title='User specified filled contours with holes')

plt.show()
User specified filled contours with holes

Total running time of the script: ( 0 minutes 1.090 seconds)

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