How to overlay a pcolormesh with binary information in Python-CodePudding

Given a 2D array

The objective is to place markers (e.g., shape, line) overlapping to the 2D images with reference to a binary 2D coordinate below

0,1,0
0,0,0
0,1,0
1,1,0

Specifically, a marker will be place if the cell is equivalent to 1.

The expected output is as below. In this example, the marker is in the form of horizontal red line. However, the marker can be of any other shape that make the code more straight forward.

May I know how to achieve this with any graphical packages in Python?

The above coordinate can be reproduced by following

import numpy as np
import matplotlib.pyplot as plt
np.random.seed(0)
X=np.random.randint(256, size=(4, 3))
arrshape=np.random.randint(2, size=(4, 3))
fig = plt.figure(figsize=(8,6))
plt.pcolormesh(X,cmap="plasma")
plt.title("Plot 2D array")
plt.colorbar()
plt.show()

CodePudding user response：

You can throw in a scatter:

x,y = X.shape
xs,ys = np.ogrid[:x,:y]
# the non-zero coordinates
u = np.argwhere(arrshape)

plt.scatter(ys[:,u[:,1]].ravel() .5, 
            xs[u[:,0]].ravel() 0.5,
            marker='x', color='r', s=100)

Output:

CodePudding user response：

One way to do it is with matplotlib

import numpy as np
import matplotlib.pyplot as plt
np.random.seed(0)
X=np.random.randint(256, size=(4, 3))
arrshape=np.random.randint(2, size=(4, 3))
fig = plt.figure(figsize=(8,6))
plt.pcolormesh(X,cmap="plasma")
plt.title("Plot 2D array")
plt.colorbar()

markers = [
    [0,1,0],
    [0,0,0],
    [0,1,0],
    [1,1,0]]

draw = []
for y, row in enumerate(markers):
    prev = 0
    for x, v in enumerate(row):
        if v == 1:
            plt.plot([x 0.25, x 0.75], [y 0.5, y 0.5], 'r-', linewidth=5)
            if prev == 1:
                plt.plot([x-0.5, x 0.5], [y 0.5, y 0.5], 'r-', linewidth=5)
        prev = v

plt.show()

Output: (Since your markers are upside-down)