Plot two histograms on single chart with matplotlib

Question

I created a histogram plot using data from a file and no problem. Now I wanted to superpose data from another file in the same histogram, so I do something like this

n,bins,patchs = ax.hist(mydata1,100) n,bins,patchs = ax.hist(mydata2,100) 

but the problem is that for each interval, only the bar with the highest value appears, and the other is hidden. I wonder how could I plot both histograms at the same time with different colors.

Answer 1

Here you have a working example:

import random import numpy from matplotlib import pyplot  x = [random.gauss(3,1) for _ in range(400)] y = [random.gauss(4,2) for _ in range(400)]  bins = numpy.linspace(-10, 10, 100)  pyplot.hist(x, bins, alpha=0.5, label='x') pyplot.hist(y, bins, alpha=0.5, label='y') pyplot.legend(loc='upper right') pyplot.show() 

Answer 2

The accepted answers gives the code for a histogram with overlapping bars, but in case you want each bar to be side-by-side (as I did), try the variation below:

import numpy as np import matplotlib.pyplot as plt plt.style.use('seaborn-deep')  x = np.random.normal(1, 2, 5000) y = np.random.normal(-1, 3, 2000) bins = np.linspace(-10, 10, 30)  plt.hist([x, y], bins, label=['x', 'y']) plt.legend(loc='upper right') plt.show() 

Reference: http://matplotlib.org/examples/statistics/histogram_demo_multihist.html

EDIT [2018/03/16]: Updated to allow plotting of arrays of different sizes, as suggested by @stochastic_zeitgeist