Colorplot of 2D array matplotlib

Question

So, I thought this was going to be really simple, but I’ve been having a lot of difficult finding exactly what I’m looking for in a comprehensible example.

Basically I want to make phase plots, so assuming I have a 2d array, how can I get matplotlib to convert this to a plot that I can attach titles, axes, and legends (color bars) to.

I’m looking for an extremely simple bare bones solution that only uses what is required that will work with any 2D array.

I’m certain this is simple and I’m just being thick somehow, but I’m really having a lot of trouble with this.

I have been tooling with the examples, but they don’t seem well suited to what I’m trying to do: I like the general appearance of this graph, I’d just like to be able to pass in a 2dArray and have this same result:

import numpy as np
import matplotlib as ml
import matplotlib.pyplot as plt

H = [[1,2,3,4][5,6,7,8][9,10,11,12][13,14,15,16]]

fig = plt.figure(figsize=(6, 3.2))

ax = fig.add_subplot(111)
ax.set_title('colorMap')
X,Y = np.meshgrid(xedges, yedges)
plt.pcolormesh(X, Y, H)
ax.set_aspect('equal')

cax = fig.add_axes([0.12, 0.1, 0.78, 0.8])
cax.get_xaxis().set_visible(False)
cax.get_yaxis().set_visible(False)
cax.patch.set_alpha(0)
cax.set_frame_on(False)
plt.colorbar(orientation='vertical')
plt.show()

Asked By: Slater Victoroff

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Source

Answer 1

I’m afraid your posted example is not working, since X and Y aren’t defined. So instead of pcolormesh let’s use imshow:

import numpy as np
import matplotlib.pyplot as plt

H = np.array([[1, 2, 3, 4],
              [5, 6, 7, 8],
              [9, 10, 11, 12],
              [13, 14, 15, 16]])  # added some commas and array creation code

fig = plt.figure(figsize=(6, 3.2))

ax = fig.add_subplot(111)
ax.set_title('colorMap')
plt.imshow(H)
ax.set_aspect('equal')

cax = fig.add_axes([0.12, 0.1, 0.78, 0.8])
cax.get_xaxis().set_visible(False)
cax.get_yaxis().set_visible(False)
cax.patch.set_alpha(0)
cax.set_frame_on(False)
plt.colorbar(orientation='vertical')
plt.show()

Answered By: heltonbiker

Answer 2

Here is the simplest example that has the key lines of code:

import numpy as np 
import matplotlib.pyplot as plt

H = np.array([[1, 2, 3, 4],
          [5, 6, 7, 8],
          [9, 10, 11, 12],
          [13, 14, 15, 16]])

plt.imshow(H, interpolation='none')
plt.show()

EDIT: (1/2023) Still working with Python 3.9.13

Answered By: user185160

Colorplot of 2D array matplotlib

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