Matplotlib uses the matplotlibrc file to store default values for various environment and figure parameters used across matplotlib functionality. Hence, this file is very long. These default values are customizable to apply for all the plots within a session.

You can use the print(matplotlib.rcParams) command to get all the default parameter settings from this file.

The matplotlib.rcParams command is used to change these default values to any other supported values, one parameter at a time. The matplotlib.rc command is used to set default values for multiple parameters within a specific group, for example, lines, font, text, and so on. Finally, the matplotlib.rcdefaults() command is used to restore default parameters.

The following code block provides the path to the file containing all configuration the parameters:

# Get the location of matplotlibrc file
import matplotlib
matplotlib.matplotlib_fname()

You should see the directory path like the one that follows. The exact directory path depends on your installation:

'C:\\Anaconda3\\envs\\keras35\\lib\\site-packages\\matplotlib\\mpl-
    data\\matplotlibrc'

The following block of code along with comments helps you to understand the process of changing and resetting default environment variables:

1. Import the matplotlib.pyplot package with the plt synonym:

import matplotlib.pyplot as plt

2. Load x and y variables from same test.csv file that we used in the preceding recipe:

x, y = np.loadtxt ('test.csv', unpack = True, usecols = (0,1), 
                    delimiter = ',')

3. Change the default values for multiple parameters within the group 'lines':

matplotlib.rc('lines', linewidth=4, linestyle='-', marker='*')

4. Change the default values for parameters individually:

matplotlib.rcParams['lines.markersize'] = 20
matplotlib.rcParams['font.size'] = '15.0'

5. Plot the graph:

plt.plot(x,y)

6. Display the graph:

plt.show()

The following is the output that will be obtained:

The matplotlib.rc and matplotlib.rcParams commands overwrite the default values for specified parameters as arguments in these commands. These new values will be used by the pyplot tool while plotting the graph.

You can reset all the parameters to their default values, using the rsdefaults() command, as shown in the following block:

# To restore all default parameters
matplotlib.rcdefaults() 
plt.plot(x,y)
plt.show()

The graph will look as follows:

.