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python pcolor on an irregular retangular grid

Can I use pcolor to plot data on irregular grid with rectangular cells? I don't want to plot those cells where the data are absent.

2 Answers
2

You can treat it like an image:

import numpy as np
a = 3 # height of each rectangle
b = 14 # width of each rectangle
n = 5 # number of rectangles in each direction
arr = 255*np.ones((n*a,n*b,3),dtype='uint8') #white image array

# generate random colors (RGB format)
colors = np.random.randint(0,255,size=(n,n,3))

# now fill the image array with rectangles of color
for i in range(n):
for j in range(n):
arr[a*i:a*(i+1),b*j:b*(j+1)] = colors[i,j]

# and plot the resulting image
import matplotlib.pyplot as plt
plt.imshow(arr)
plt.show()


edit:
if any cells don't have data, you simply don't fill them with a new color: They're white by default

arr

import numpy as np
import matplotlib.pyplot as plt

x=np.linspace(-10,10,21)
y=np.linspace(-10,10,21)
X,Y=np.meshgrid(x,y)

#synthetic data
x_c=(x[0:-1]+x[1:])*0.5#center of each cell
y_c=(y[0:-1]+y[1:])*0.5
Xc,Yc=np.meshgrid(x_c,y_c)
Z=Xc**2+Yc**2

#values in those cells without data are set as np.nan
Z[9:11,9]=np.nan
Z[0,0:3]=np.nan
Z[3:4,0]=np.nan

#plot the data
fig=plt.figure()
plt.pcolor(X,Y,Z)
plt.show()


Just take the cells without data as nan (not a number).

enter image description here

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