[matplotlib]How to Save a Plot to a File

This article shows how to save a plot using matplotlib.

How to Save a Plot to a File in Matplotlib

I show how to save a plot to a file.

Matplotlib provides "matplotlib.pyplot.savefig" method for saving plot.

First, I will show the use of the "savefig" method.

Then, I will show the example code.

How to Use "savefig" method

I show how to use "savefig" method.

The way to use of "savefig" method is described in matplotlib documentation.

Specify a file path as an argument.

The image formats that can be saved are as follows.

The Example Code to Save a Plot

I show the example code to save a plot.

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


x1 = np.random.normal(0, 10, 1000)
x2 = np.random.normal(20, 20, 1000)


fig = plt.figure(figsize = (5,5), facecolor='lightblue')

plt.xlabel('X')
plt.ylabel('Y')

plt.hist(x1,  bins=30, range=(-50, 100), ec='black', alpha = 0.5, label='x1')
plt.hist(x2,  bins=30, range=(-50, 100), ec='black', alpha = 0.5, label='x2')

plt.legend()

plt.show()


path_dir = pathlib.Path(r'test')
path_img = path_dir.joinpath('img.png')

fig.savefig(path_img)

The above code generates the following graph.

> x1 = np.random.normal(0, 10, 1000)
> x2 = np.random.normal(20, 20, 1000)

Random numbers are generated according to a normal distribution.

> fig = plt.figure(figsize = (5,5), facecolor='lightblue')

The figure object is generated.

> plt.xlabel('X')
> plt.xlabel('Y')

Labels are added.

> plt.hist(x1, bins=30, range=(-50, 100), ec='black', alpha = 0.5, label='x1')
> plt.hist(x2, bins=30, range=(-50, 100), ec='black', alpha = 0.5, label='x2')

Specify data in list type as an argument to plot histograms.

> plt.legend()

Legend is added.

> path_dir = pathlib.Path(r'test')
> path_img = path_dir.joinpath('img.png')

The path object is generated by using "pathlib" module.

> fig.savefig(path_img)

The plot is saved as a image file by using "savefig" method.

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