I have data that results in multiple lines being plotted, I want to give these lines a single label in my legend. I think this can be better demonstrated using the example below,
a = np.array([[ 3.57, 1.76, 7.42, 6.52],
[ 1.57, 1.2 , 3.02, 6.88],
[ 2.23, 4.86, 5.12, 2.81],
[ 4.48, 1.38, 2.14, 0.86],
[ 6.68, 1.72, 8.56, 3.23]])
plt.plot(a[:,::2].T, a[:, 1::2].T, 'r', label='data_a')
plt.legend(loc='best')
As you can see at Out[23] the plot resulted in 5 distinct lines. The resulting plot looks like this
Is there any way that I can tell the plot method to avoid multiple labels? I don't want to use custom legend (where you specify the label and the line shape all at once) as much as I can.
I'd make a small helper function personally, if i planned on doing it often;
from matplotlib import pyplot
import numpy
a = numpy.array([[ 3.57, 1.76, 7.42, 6.52],
[ 1.57, 1.2 , 3.02, 6.88],
[ 2.23, 4.86, 5.12, 2.81],
[ 4.48, 1.38, 2.14, 0.86],
[ 6.68, 1.72, 8.56, 3.23]])
def plotCollection(ax, xs, ys, *args, **kwargs):
ax.plot(xs,ys, *args, **kwargs)
if "label" in kwargs.keys():
#remove duplicates
handles, labels = pyplot.gca().get_legend_handles_labels()
newLabels, newHandles = [], []
for handle, label in zip(handles, labels):
if label not in newLabels:
newLabels.append(label)
newHandles.append(handle)
pyplot.legend(newHandles, newLabels)
ax = pyplot.subplot(1,1,1)
plotCollection(ax, a[:,::2].T, a[:, 1::2].T, 'r', label='data_a')
plotCollection(ax, a[:,1::2].T, a[:, ::2].T, 'b', label='data_b')
pyplot.show()
An easier (and IMO clearer) way to remove duplicates (than what you have) from the handles
and labels
of the legend is this:
handles, labels = pyplot.gca().get_legend_handles_labels()
newLabels, newHandles = [], []
for handle, label in zip(handles, labels):
if label not in newLabels:
newLabels.append(label)
newHandles.append(handle)
pyplot.legend(newHandles, newLabels)