When I use matplotlib in jupyter notebook,it always raise " matplotlib is currently using a non-GUI backend" error?

Question

import matplotlib.pyplot as pl %matplot inline def learning_curves(X_train, y_train, X_test, y_test): """ Calculates the performance of several models with varying sizes of training data.     The learning and testing error rates for each model are then plotted. """  print ("Creating learning curve graphs for max_depths of 1, 3, 6, and 10. . .")  # Create the figure window fig = pl.figure(figsize=(10,8))  # We will vary the training set size so that we have 50 different sizes sizes = np.rint(np.linspace(1, len(X_train), 50)).astype(int) train_err = np.zeros(len(sizes)) test_err = np.zeros(len(sizes))  # Create four different models based on max_depth for k, depth in enumerate([1,3,6,10]):      for i, s in enumerate(sizes):          # Setup a decision tree regressor so that it learns a tree with max_depth = depth         regressor = DecisionTreeRegressor(max_depth = depth)          # Fit the learner to the training data         regressor.fit(X_train[:s], y_train[:s])          # Find the performance on the training set         train_err[i] = performance_metric(y_train[:s], regressor.predict(X_train[:s]))          # Find the performance on the testing set         test_err[i] = performance_metric(y_test, regressor.predict(X_test))      # Subplot the learning curve graph     ax = fig.add_subplot(2, 2, k+1)      ax.plot(sizes, test_err, lw = 2, label = 'Testing Error')     ax.plot(sizes, train_err, lw = 2, label = 'Training Error')     ax.legend()     ax.set_title('max_depth = %s'%(depth))     ax.set_xlabel('Number of Data Points in Training Set')     ax.set_ylabel('Total Error')     ax.set_xlim([0, len(X_train)])  # Visual aesthetics fig.suptitle('Decision Tree Regressor Learning Performances', fontsize=18, y=1.03) fig.tight_layout() fig.show() 

when I run the learning_curves() function, it shows:

UserWarning:C:\Users\Administrator\Anaconda3\lib\site-packages\matplotlib\figure.py:397: UserWarning: matplotlib is currently using a non-GUI backend, so cannot show the figure

Answer 1

You don't need the line of "fig.show()". Just remove it. Then it will be no warning message.

Answer 2

adding %matplotlib inline while importing helps for smooth plots in notebook

%matplotlib inline import matplotlib.pyplot as plt 

%matplotlib inline sets the backend of matplotlib to the 'inline' backend: With this backend, the output of plotting commands is displayed inline within frontends like the Jupyter notebook, directly below the code cell that produced it. The resulting plots will then also be stored in the notebook document.