testbed/matplotlib__matplotlib/galleries/examples/misc/contour_manual.py

"""
==============
Manual Contour
==============

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

import matplotlib.pyplot as plt

import matplotlib.cm as cm
from matplotlib.contour import ContourSet
from matplotlib.path import Path

# %%
# 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')

# %%
# 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.

fig, ax = plt.subplots()
filled01 = [[[0, 0], [3, 0], [3, 3], [0, 3], [1, 1], [1, 2], [2, 2], [2, 1]]]
M = Path.MOVETO
L = Path.LINETO
kinds01 = [[M, L, L, L, M, L, L, L]]
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()