Matplotlib - Histogram
A histogram is an accurate representation of the distribution of numerical data. It is an estimate of the probability distribution of a continuous variable. It is a kind of bar graph.
To construct a histogram, follow these steps −
- Bin the range of values.
- Divide the entire range of values into a series of intervals.
- Count how many values fall into each interval.
The bins are usually specified as consecutive, non-overlapping intervals of a variable.
The matplotlib.pyplot.hist() function plots a histogram. It computes and draws the histogram of x.
Parameters
The following table lists down the parameters for a histogram −
| x |
array or sequence of arrays |
| bins |
integer or sequence or ‘auto’, optional |
| optional parameters |
| range |
The lower and upper range of the bins. |
| density |
If True, the first element of the return tuple will be the counts normalized to form a probability density |
| cumulative |
If True, then a histogram is computed where each bin gives the counts in that bin plus all bins for smaller values. |
| histtype |
The type of histogram to draw. Default is ‘bar’
- ‘bar’ is a traditional bar-type histogram. If multiple data are given the bars are arranged side by side.
- ‘barstacked’ is a bar-type histogram where multiple data are stacked on top of each other.
- ‘step’ generates a lineplot that is by default unfilled.
- ‘stepfilled’ generates a lineplot that is by default filled.
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Following example plots a histogram of marks obtained by students in a class. Four bins, 0-25, 26-50, 51-75, and 76-100 are defined. The Histogram shows number of students falling in this range.
from matplotlib import pyplot as plt
import numpy as np
fig,ax = plt.subplots(1,1)
a = np.array([22,87,5,43,56,73,55,54,11,20,51,5,79,31,27])
ax.hist(a, bins = [0,25,50,75,100])
ax.set_title("histogram of result")
ax.set_xticks([0,25,50,75,100])
ax.set_xlabel('marks')
ax.set_ylabel('no. of students')
plt.show()
The plot appears as shown below −
