What kind of plot from matplotlib should I use?

Question

I am programming in Python 3 and I have data structured like this:

coordinates = [(0.15,0.25),(0.35,0.25),(0.55,0.45),(0.65,0.10),(0.15,0.25)]

These are coordinates. Within each pair, the first number is the x coordinate and the second one the y coordinate. Some of the coordinates repeat themselves. I want to plot these data like this:

The coordinates that are most frequently found should appear either as higher intensity (i.e., brighter) points or as points with a different color (for example, red for very frequent coordinates and blue for very infrequent coordinates). Don't worry about the circle and semicircle. That's irrelevant. Is there a matplotlib plot that can do this? Scatter plots do not work because they do not report on the frequency with which each coordinate is found. They just create a cloud.

Use pandas to count the frequency with which each x-y pair appears, then a [scatter plot](https://stackoverflow.com/q/50527658/8881141). — Mr. T, Dec 29 '20 at 17:54

score 0 · Accepted Answer · answered Jan 06 '21 at 15:26

The answer is:

import matplotlib.pyplot as plt
from scipy.stats import kde
import numpy as np

xvalues = np.random.normal(loc=0.5,scale=0.01,size=50000)
yvalues = np.random.normal(loc=0.25,scale=0.1,size=50000)

nbins=300
k = kde.gaussian_kde([xvalues,yvalues])
xi, yi = np.mgrid[0:1:nbins*1j,0:1:nbins*1j]
zi = k(np.vstack([xi.flatten(),yi.flatten()]))
fig, ax = plt.subplots()
ax.pcolormesh(xi, yi, zi.reshape(xi.shape), shading='auto', cmap=plt.cm.hot)
x = np.arange(0.0,1.01,0.01,dtype=np.float64)
y = np.sqrt((0.5*0.5)-((x-0.5)*(x-0.5)))
ax.axis([0,1,0,0.55])
ax.set_ylabel('S', fontsize=16)
ax.set_xlabel('G', fontsize=16)
ax.tick_params(labelsize=12, width=3)
ax.plot(x,y,'w--')
plt.show()

What kind of plot from matplotlib should I use?

1 Answers1