How to save figure in matplotlib pyplot

In this article, you will learn to save matplotlib pyplot figure in a different format.
Matplotlib is probably the single most used Python package for 2D-graphics. It provides both a very quick way to visualize data from Python and publication-quality figures in many formats.

For this task, first we need to import the matplotlib module and data to plot the graph -

import matplotlib.pyplot as plt
# Data to plot 
x = [2, 3, 4, 5, 6, 8, 9, 10]
y1 = [17, 15, 6, 12, 10, 25, 12, 14]
y2 = [13, 12, 8, 7, 14, 18, 20, 11]
y3 = [15, 10, 11, 8, 5, 12, 20, 23]

plt.plot(x,y1, marker = 'o', color='#170337')
plt.plot(x,y2, marker = 'x', color='#FAA50A')
plt.plot(x,y3, marker = '+', color='#0496ff')

Next, we control over the plotting window GUI, using the figure() method. It has several parameters that determine how the figure look like. Here, figsize is the figure size (width, height) in inches. We set the size of our figure to be 8 by 5 inches. The fig.add_subplot() adds a subplot to the current figure. It returns a figure object. Using this, we set a title and labels for the x and y axis and a grid pattern.

figsize = (8, 5) 
fig = plt.figure(figsize=figsize)

ax = fig.add_subplot(111) 
ax.set_title('Plot') 
ax.set_xlabel('measured')
ax.set_ylabel('calculated')
ax.grid(True)

matplotlib.pyplot.savefig

The matplotlib.pyplot.savefig is used to save the current figure in a different file format. It has the following syntax with basic parameters -

savefig(fname, dpi=None, facecolor='w', edgecolor='w', format=None,
        transparent=False, quality=None, optimize=Flase)

Here, fname is the file path, dpi is the resolution in dots per inch, facecolor is the face color, edgecolor is the edgecolor of the figure, format is the file format, e.g., 'png', 'pdf', 'svg' and the transparent is a boolean value. If True, the axes patches will all be transparent, the figure patch will also be transparent unless facecolor and/or edgecolor are specified via kwargs. The quality is the image quality, on a scale from 1 (worst) to 95 (best). The optimize is optional and only applicable in JPG file format.

Save matplotlib figure as JPG

Here is the complete code to save the generated matplotlib figure as jpg -

import matplotlib.pyplot as plt

figsize = (8, 5) 
fig = plt.figure(figsize=figsize)

ax = fig.add_subplot(111) 
ax.set_title('Plot') 
ax.set_xlabel('measured')
ax.set_ylabel('calculated')
ax.grid(True)

# Data to plot 
x = [2, 3, 4, 5, 6, 8, 9, 10]
y1 = [17, 15, 6, 12, 10, 25, 12, 14]
y2 = [13, 12, 8, 7, 14, 18, 20, 11]
y3 = [15, 10, 11, 8, 5, 12, 20, 23]

plt.plot(x,y1, marker = 'o', color='#170337')
plt.plot(x,y2, marker = 'x', color='#FAA50A')
plt.plot(x,y3, marker = '+', color='#0496ff')
plt.savefig('multiplot.jpg', dpi=150, quality=90, optimize=True)
plt.show()

The above code saves the following jpg file in your working directory -

Save matplotlib figure as PDF

Similarly, we can save the above plot in PDF file format.

plt.savefig('multiplot.pdf')  

Save matplotlib figure as PNG

We generally use the png format to create the transparent background. By default, matplotlib creates plot on white background. But you can also make the background transparent by passing transparent=true to the savefig() method, like -

plt.savefig('multiplot.png', dpi=200, transparent=True)  

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