Matplotlib legends in subplot

PythonMatplotlib

Python Problem Overview

I would like to put legends inside each one of the subplots below. I've tried with plt.legend but it didn't work.

Any suggestions?

Thanks in advance :-)

f, (ax1, ax2, ax3) = plt.subplots(3, sharex=True, sharey=True)
ax1.plot(xtr, color='r', label='Blue stars')
ax2.plot(ytr, color='g')
ax3.plot(ztr, color='b')
ax1.set_title('2012/09/15')
plt.legend([ax1, ax2, ax3],["HHZ 1", "HHN", "HHE"])
plt.show()

Resulting plot With the suggestion from atomh33ls:

ax1.legend("HHZ 1",loc="upper right")
ax2.legend("HHN",loc="upper right")
ax3.legend("HHE",loc="upper right")

The legend position is fixed, however it seems to have a problem with the strings, because each letter is placed in a new line.

Does anyone knows how to fix it?

enter image description here

Python Solutions

Solution 1 - Python

This should work:

ax1.plot(xtr, color='r', label='HHZ 1')
ax1.legend(loc="upper right")
ax2.plot(xtr, color='r', label='HHN')
ax2.legend(loc="upper right")
ax3.plot(xtr, color='r', label='HHE')
ax3.legend(loc="upper right")

Solution 2 - Python

What you want cannot be done, because plt.legend() places a legend in the current axes, in your case in the last one.

If, on the other hand, you can be content with placing a comprehensive legend in the last subplot, you can do like this

f, (ax1, ax2, ax3) = plt.subplots(3, sharex=True, sharey=True)
l1,=ax1.plot(x,y, color='r', label='Blue stars')
l2,=ax2.plot(x,y, color='g')
l3,=ax3.plot(x,y, color='b')
ax1.set_title('2012/09/15')
plt.legend([l1, l2, l3],["HHZ 1", "HHN", "HHE"])
plt.show()

enter image description here

Note that you pass to legend not the axes, as in your example code, but the lines as returned by the plot invocation.

PS

Of course you can invoke legend after each subplot, but in my understanding you already knew that and were searching for a method for doing it at once.

Solution 3 - Python

This does what you want and overcomes some of the problems in other answers:

import matplotlib.pyplot as plt

labels = ["HHZ 1", "HHN", "HHE"]
colors = ["r","g","b"]

f,axs = plt.subplots(3, sharex=True, sharey=True)

# ---- loop over axes ----
for i,ax in enumerate(axs):
  axs[i].plot([0,1],[1,0],color=colors[i],label=labels[i])
  axs[i].legend(loc="upper right")

plt.show()

... produces ... subplots

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Content TypeOriginal AuthorOriginal Content on Stackoverflow
QuestionCatarinaCMView Question on Stackoverflow
Solution 1 - Pythonatomh33lsView Answer on Stackoverflow
Solution 2 - PythongboffiView Answer on Stackoverflow
Solution 3 - PythoncompuphysView Answer on Stackoverflow