How to merge mesh grid points from two rectangles in python?

Question

I need to merge the mesh grids formed at two different (adjoining) rectangles. Following is the pictorial representation of the rectangle:

I can create the mesh grids of the individual rectangles. For example for the green rectangle, using the following code snippet, we can create a mesh grid.

xvalues = np.array([0, 2, 4, 6, 8, 10])
yvalues = np.array([6, 8, 10, 12])
x, y = np.meshgrid(xvalues, yvalues)
positions = np.vstack([x.ravel(), y.ravel()])
theGridPoints = (np.array(positions)).T

I can make the grid points for the blue rectangle too. However, I'm unable to join them inside a single object. I tried to join them as the sum of position1 and position2. I get the value error on the console as:

ValueError: operands could not be broadcast together with shapes (.,.) (.,.)

How can I solve it?

Answer 1

If you want to join/merge multiple np.ndarray, they need to be of the same shape. So you the number of xvalues of the blue rectangle need to be equal to the number of xvalues of the green rectangle. Same for the yvalues. Here is a short example:

xvalues_b = np.array([0, 1, 2, 3, 4, 5])
yvalues_b = np.array([0, 1*5/3, 2*5/3, 3*5/3])
x_b, y_b = np.meshgrid(xvalues_b, yvalues_b)
positions_b = np.vstack([x_b.ravel(), y_b.ravel()])
theGridPoints_b = (np.array(positions_b)).T
positions_gb = np.concatenate([positions, positions_b])

Answer 2

import numpy as np
import matplotlib.pyplot as plt

bx, by = np.mgrid[0:2, 0:5]
gx, gy = np.mgrid[0:10, 5:12]

bp = np.vstack((bx.ravel(), by.ravel()))
gp = np.vstack((gx.ravel(), gy.ravel()))

points = np.hstack((bp, gp)).T

# full grid
plt.scatter(points[:,0], points[:,1], c='orange', s=200)
# green rectangle
plt.scatter(gp.T[:,0], gp.T[:,1], c='green', s=50)
# blue rectangle
plt.scatter(bp.T[:,0], bp.T[:,1], c='blue', s=50)

plt.show()