Python real time varying heat map plotting

Question

I have a 2D grid 50*50. For each location I have an intensity value(i.e data is like (x,y,intensity) for each of those 50*50 locations). I would like to visualize the data as a heatmap.

The twist is that every second the intensity will change(for most of the locations), which means I will need to re-draw the heatmap every second. I am wondering what is the best library/approach to handle this kind of real-time varing heatmap.

Answer 1

This really depends on how you get your data, but:

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

# create the figure
fig = plt.figure()
ax = fig.add_subplot(111)
im = ax.imshow(np.random.random((50,50)))
plt.show(block=False)

# draw some data in loop
for i in range(10):
    # wait for a second
    time.sleep(1)
    # replace the image contents
    im.set_array(np.random.random((50,50)))
    # redraw the figure
    fig.canvas.draw()

This should draw 11 random 50x50 images with 1 second intervals. The essential part is im.set_array which replaces the image data and fig.canvas.draw which redraws the image onto the canvas.

---

If your data is really a list of points in the form (x, y, intensity), you can transform them into a numpy.array:

import numpy as np

# create an empty array (NaNs will be drawn transparent)
data = np.empty((50,50))
data[:,:] = np.nan

# ptlist is a list of (x, y, intensity) triplets
ptlist = np.array(ptlist)
data[ptlist[:,1].astype('int'), ptlist[:,0].astype('int')] = ptlist[:,2]