使用 matplotlib 绘制带有切割单元的二维数组

Question

I want to plot using pcolor in matplotlib something akin to the JPEG in the link. I am dealing with cut cells, which are grid cells in 2D that are split into two by some obstacle or barrier. And I need to represent water state (height, velocity) in each of those split cells, so they should be able to be different colors. I can plot the regular cells that are not split, but I am not sure how I can plot the cut cells.

Answer 1

You can first draw a normal colormesh, and then draw the second colormesh on top of it, clipped by a polygon:

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.patches import Polygon

fig, ax = plt.subplots()

# first mesh
a = np.arange(4 * 5).reshape(4, 5)
ax.pcolormesh(a, cmap='PuBu', edgecolor='k', lw=2)

# polygon for clipping
poly = Polygon(xy=np.array([[.2, 4], [2, 0], [5, 4], [.2, 4]]), facecolor='none', edgecolor='orange', linewidth=2)
ax.add_patch(poly)

# second mesh
b = np.random.rand(4, 5)
mesh = ax.pcolormesh(b, cmap='spring', edgecolor='k', lw=2)
mesh.set_clip_path(poly)

ax.set_xticks([])
ax.set_yticks([])

ax.set_aspect('equal')
plt.show()