increase the linewidth of the legend lines in matplotlib

Question

I know that if I change the linewidth of a line, that is automatically updated in the legend. However I would like to just change the legend linewidth without affecting the plot.

Answer 1

Here's a simple example of how to do it:

import numpy as np import matplotlib.pyplot as plt  # make some data x = np.linspace(0, 2*np.pi) y1 = np.sin(x) y2 = np.cos(x)  # plot sin(x) and cos(x) p1 = plt.plot(x, y1, 'b-', linewidth=1.0) p2 = plt.plot(x, y2, 'r-', linewidth=1.0)  # make a legend for both plots leg = plt.legend([p1, p2], ['sin(x)', 'cos(x)'], loc=1)  # set the linewidth of each legend object for legobj in leg.legendHandles:     legobj.set_linewidth(2.0)  plt.show() 

Answer 2

@Brendan Wood's method use the api provided by pyplot. In matplotlib, the object oriented style using axes is prefered. The following is how you can achieve this using axes method.

import numpy as np import matplotlib.pyplot as plt  # make some data x = np.linspace(0, 2*np.pi) y1 = np.sin(x) y2 = np.cos(x)  fig, ax = plt.subplots() ax.plot(x, y1, linewidth=1.0, label='sin(x)') ax.plot(x, y2, linewidth=1.0, label='cos(x)') leg = ax.legend()  for line in leg.get_lines():     line.set_linewidth(4.0)  plt.show() 

The produced plot is shown below,