python – How to put the legend out of the plot
python – How to put the legend out of the plot
There are a number of ways to do what you want. To add to what @inalis and @Navi already said, you can use the bbox_to_anchor
keyword argument to place the legend partially outside the axes and/or decrease the font size.
Before you consider decreasing the font size (which can make things awfully hard to read), try playing around with placing the legend in different places:
So, lets start with a generic example:
import matplotlib.pyplot as plt
import numpy as np
x = np.arange(10)
fig = plt.figure()
ax = plt.subplot(111)
for i in xrange(5):
ax.plot(x, i * x, label=$y = %ix$ % i)
ax.legend()
plt.show()
If we do the same thing, but use the bbox_to_anchor
keyword argument we can shift the legend slightly outside the axes boundaries:
import matplotlib.pyplot as plt
import numpy as np
x = np.arange(10)
fig = plt.figure()
ax = plt.subplot(111)
for i in xrange(5):
ax.plot(x, i * x, label=$y = %ix$ % i)
ax.legend(bbox_to_anchor=(1.1, 1.05))
plt.show()
Similarly, make the legend more horizontal and/or put it at the top of the figure (Im also turning on rounded corners and a simple drop shadow):
import matplotlib.pyplot as plt
import numpy as np
x = np.arange(10)
fig = plt.figure()
ax = plt.subplot(111)
for i in xrange(5):
line, = ax.plot(x, i * x, label=$y = %ix$%i)
ax.legend(loc=upper center, bbox_to_anchor=(0.5, 1.05),
ncol=3, fancybox=True, shadow=True)
plt.show()
Alternatively, shrink the current plots width, and put the legend entirely outside the axis of the figure (note: if you use tight_layout()
, then leave out ax.set_position()
:
import matplotlib.pyplot as plt
import numpy as np
x = np.arange(10)
fig = plt.figure()
ax = plt.subplot(111)
for i in xrange(5):
ax.plot(x, i * x, label=$y = %ix$%i)
# Shrink current axis by 20%
box = ax.get_position()
ax.set_position([box.x0, box.y0, box.width * 0.8, box.height])
# Put a legend to the right of the current axis
ax.legend(loc=center left, bbox_to_anchor=(1, 0.5))
plt.show()
And in a similar manner, shrink the plot vertically, and put a horizontal legend at the bottom:
import matplotlib.pyplot as plt
import numpy as np
x = np.arange(10)
fig = plt.figure()
ax = plt.subplot(111)
for i in xrange(5):
line, = ax.plot(x, i * x, label=$y = %ix$%i)
# Shrink current axiss height by 10% on the bottom
box = ax.get_position()
ax.set_position([box.x0, box.y0 + box.height * 0.1,
box.width, box.height * 0.9])
# Put a legend below current axis
ax.legend(loc=upper center, bbox_to_anchor=(0.5, 0.05),
fancybox=True, shadow=True, ncol=5)
plt.show()
Have a look at the matplotlib legend guide. You might also take a look at plt.figlegend()
.
Placing the legend (bbox_to_anchor
)
A legend is positioned inside the bounding box of the axes using the loc
argument to plt.legend
.
E.g. loc=upper right
places the legend in the upper right corner of the bounding box, which by default extents from (0,0)
to (1,1)
in axes coordinates (or in bounding box notation (x0,y0, width, height)=(0,0,1,1)
).
To place the legend outside of the axes bounding box, one may specify a tuple (x0,y0)
of axes coordinates of the lower left corner of the legend.
plt.legend(loc=(1.04,0))
A more versatile approach is to manually specify the bounding box into which the legend should be placed, using the bbox_to_anchor
argument. One can restrict oneself to supply only the (x0, y0)
part of the bbox. This creates a zero span box, out of which the legend will expand in the direction given by the loc
argument. E.g.
plt.legend(bbox_to_anchor=(1.04,1), loc=upper left)
places the legend outside the axes, such that the upper left corner of the legend is at position (1.04,1)
in axes coordinates.
Further examples are given below, where additionally the interplay between different arguments like mode
and ncols
are shown.
l1 = plt.legend(bbox_to_anchor=(1.04,1), borderaxespad=0)
l2 = plt.legend(bbox_to_anchor=(1.04,0), loc=lower left, borderaxespad=0)
l3 = plt.legend(bbox_to_anchor=(1.04,0.5), loc=center left, borderaxespad=0)
l4 = plt.legend(bbox_to_anchor=(0,1.02,1,0.2), loc=lower left,
mode=expand, borderaxespad=0, ncol=3)
l5 = plt.legend(bbox_to_anchor=(1,0), loc=lower right,
bbox_transform=fig.transFigure, ncol=3)
l6 = plt.legend(bbox_to_anchor=(0.4,0.8), loc=upper right)
Details about how to interpret the 4tuple argument to bbox_to_anchor
, as in l4
, can be found in this question. The mode=expand
expands the legend horizontally inside the bounding box given by the 4tuple. For a vertically expanded legend, see this question.
Sometimes it may be useful to specify the bounding box in figure coordinates instead of axes coordinates. This is shown in the example l5
from above, where the bbox_transform
argument is used to put the legend in the lower left corner of the figure.
Postprocessing
Having placed the legend outside the axes often leads to the undesired situation that it is completely or partially outside the figure canvas.
Solutions to this problem are:

Adjust the subplot parameters
One can adjust the subplot parameters such, that the axes take less space inside the figure (and thereby leave more space to the legend) by usingplt.subplots_adjust
. E.g.plt.subplots_adjust(right=0.7)
leaves 30% space on the righthand side of the figure, where one could place the legend.

Tight layout
Usingplt.tight_layout
Allows to automatically adjust the subplot parameters such that the elements in the figure sit tight against the figure edges. Unfortunately, the legend is not taken into account in this automatism, but we can supply a rectangle box that the whole subplots area (including labels) will fit into.plt.tight_layout(rect=[0,0,0.75,1])

Saving the figure with
bbox_inches = tight
The argumentbbox_inches = tight
toplt.savefig
can be used to save the figure such that all artist on the canvas (including the legend) are fit into the saved area. If needed, the figure size is automatically adjusted.plt.savefig(output.png, bbox_inches=tight)

automatically adjusting the subplot params
A way to automatically adjust the subplot position such that the legend fits inside the canvas without changing the figure size can be found in this answer: Creating figure with exact size and no padding (and legend outside the axes)
Comparison between the cases discussed above:
Alternatives
A figure legend
One may use a legend to the figure instead of the axes, matplotlib.figure.Figure.legend
. This has become especially useful for matplotlib version >=2.1, where no special arguments are needed
fig.legend(loc=7)
to create a legend for all artists in the different axes of the figure. The legend is placed using the loc
argument, similar to how it is placed inside an axes, but in reference to the whole figure – hence it will be outside the axes somewhat automatically. What remains is to adjust the subplots such that there is no overlap between the legend and the axes. Here the point Adjust the subplot parameters from above will be helpful. An example:
import numpy as np
import matplotlib.pyplot as plt
x = np.linspace(0,2*np.pi)
colors=[#7aa0c4,#ca82e1 ,#8bcd50,#e18882]
fig, axes = plt.subplots(ncols=2)
for i in range(4):
axes[i//2].plot(x,np.sin(x+i), color=colors[i],label=y=sin(x+{}).format(i))
fig.legend(loc=7)
fig.tight_layout()
fig.subplots_adjust(right=0.75)
plt.show()
Legend inside dedicated subplot axes
An alternative to using bbox_to_anchor
would be to place the legend in its dedicated subplot axes (lax
).
Since the legend subplot should be smaller than the plot, we may use gridspec_kw={width_ratios:[4,1]}
at axes creation.
We can hide the axes lax.axis(off)
but still put a legend in. The legend handles and labels need to obtained from the real plot via h,l = ax.get_legend_handles_labels()
, and can then be supplied to the legend in the lax
subplot, lax.legend(h,l)
. A complete example is below.
import matplotlib.pyplot as plt
plt.rcParams[figure.figsize] = 6,2
fig, (ax,lax) = plt.subplots(ncols=2, gridspec_kw={width_ratios:[4,1]})
ax.plot(x,y, label=y=sin(x))
....
h,l = ax.get_legend_handles_labels()
lax.legend(h,l, borderaxespad=0)
lax.axis(off)
plt.tight_layout()
plt.show()
This produces a plot, which is visually pretty similar to the plot from above:
We could also use the first axes to place the legend, but use the bbox_transform
of the legend axes,
ax.legend(bbox_to_anchor=(0,0,1,1), bbox_transform=lax.transAxes)
lax.axis(off)
In this approach, we do not need to obtain the legend handles externally, but we need to specify the bbox_to_anchor
argument.
Further reading and notes:
 Consider the matplotlib legend guide with some examples of other stuff you want to do with legends.
 Some example code for placing legends for pie charts may directly be found in answer to this question: Python – Legend overlaps with the pie chart
 The
loc
argument can take numbers instead of strings, which make calls shorter, however, they are not very intuitively mapped to each other. Here is the mapping for reference:
python – How to put the legend out of the plot
Just call legend()
call after the plot()
call like this:
# matplotlib
plt.plot(...)
plt.legend(loc=center left, bbox_to_anchor=(1, 0.5))
# Pandas
df.myCol.plot().legend(loc=center left, bbox_to_anchor=(1, 0.5))
Results would look something like this: