Question

I would like to use Matplotlib to generate a scatter plot with a huge amount of data (about 3 million points). Actually I’ve 3 vectors with the same dimension and I use to plot in the following way.

import matplotlib.pyplot as plt
import numpy as np
from numpy import *
from matplotlib import rc
import pylab
from pylab import * 
fig = plt.figure()
fig.subplots_adjust(bottom=0.2)
ax = fig.add_subplot(111)
plt.scatter(delta,vf,c=dS,alpha=0.7,cmap=cm.Paired)

Nothing special actually. But it takes too long to generate it actually (I’m working on my MacBook Pro 4 GB RAM with Python 2.7 and Matplotlib 1.0). Is there any way to improve the speed?

Answer 1

You could take the heatmap approach shown here. In this example the color represents the quantity of data in the bin, not the median value of the dS array, but that should be easy to change. More later if you are interested.