I want to plot a line against dataset that is actually two lines that are very close together, so I am plotting it with plt.fill. Now, I want to adjust the width of the line of the legend for the fillplot to have a similar width to the line in plt.plot. I tried using linewidth= 0.2, but with linewidth I can only change the width in the plt.plot legend.

I changed the original data to the area between these arrays, because I didn't want to upload the data file. Also changing the data of a measurement that I am comparing my theory against seems disingenuous, so I probably shouldn't do that.

import matplotlib.pyplot as plt
import numpy as np
a_seq = [0.,0.5, 1.5 ,2.,  2.5, 3.,  3.5, 4.,  4.,  4. ]
l1 = [0.0, 0.0, 1.0, 1.0, 1.0, 2.0, 3.0, 4.0, 4.0, 4.0]
l2 = [0.0, 0.2, 1.1, 1.2, 1.2, 2.1, 3.2, 4.0, 4.0, 4.0]
plt.plot(np.arange(0,len(a_seq)),a_seq)
#plt.plot(l1)
#plt.plot(l2)
plt.fill_between( np.arange(0,len(l1)), l2, l1, alpha=0.5)
plt.legend(['line3','line4'])
plt.show()

CodePudding user response：

You need to access that legend object with legendHandles and then set the height of it with set_height to your desired height, like so:

import matplotlib.pyplot as plt
import numpy as np
a_seq = [0.,0.5, 1.5 ,2.,  2.5, 3.,  3.5, 4.,  4.,  4. ]
l1 = [0.0, 0.0, 1.0, 1.0, 1.0, 2.0, 3.0, 4.0, 4.0, 4.0]
l2 = [0.0, 0.2, 1.1, 1.2, 1.2, 2.1, 3.2, 4.0, 4.0, 4.0]
plt.plot(np.arange(0,len(a_seq)),a_seq)
plt.fill_between( np.arange(0,len(l1)), l2, l1, alpha=0.5)
legend = plt.legend(['line3','line4'])
legend.legendHandles[1].set_height(2.0)
plt.show()

Output: