Some features of the histogram (hist) function

In addition to the basic histogram, this demo shows a few optional features:

  • Setting the number of data bins.
  • The density parameter, which normalizes bin heights so that the integral of the histogram is 1. The resulting histogram is an approximation of the probability density function.
  • Setting the face color of the bars.
  • Setting the opacity (alpha value).

Selecting different bin counts and sizes can significantly affect the shape of a histogram. The Astropy docs have a great section on how to select these parameters.

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


# example data
mu = 100  # mean of distribution
sigma = 15  # standard deviation of distribution
x = mu + sigma * np.random.randn(437)

num_bins = 50

fig, ax = plt.subplots()

# the histogram of the data
n, bins, patches = ax.hist(x, num_bins, density=True)

# add a 'best fit' line
y = ((1 / (np.sqrt(2 * np.pi) * sigma)) *
     np.exp(-0.5 * (1 / sigma * (bins - mu))**2))
ax.plot(bins, y, '--')
ax.set_ylabel('Probability density')
ax.set_title(r'Histogram of IQ: $\mu=100$, $\sigma=15$')

# Tweak spacing to prevent clipping of ylabel
Histogram of IQ: $\mu=100$, $\sigma=15$


The use of the following functions and methods is shown in this example:


<function Axes.set_ylabel at 0x7f280fea3af0>

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