J H J H - 18 days ago 6
Python Question

Python Seaborn Matplotlib setting line style as legend

I have the following plot build with Python and Seaborn using factorplot() method. Is it possible to use the line style as a legend to replace the legend based on line color on the right? enter image description here

graycolors = sns.mpl_palette('Greys_r', 4)
g = sns.factorplot(x="k", y="value", hue="class", palette=graycolors, data=df, linestyles=["-", "--"])


Furthermore i'm trying to get both lines in black color using the color="black" parameter in my factorplot method but this results in an exception "factorplot() got an unexpected keyword argument 'color'". How can i paint both lines in the same color and seperate them by the linestyle only?

Thank you

Answer

I have been looking for a solution trying to put the linestyle in the legend like matplotlib, but I have not yet found how to do this in seaborn. However, to make the data clear in the legend I have used different markers:

import seaborn as sns
import numpy as np
import pandas as pd

# creating some data
n = 11
x = np.linspace(0,2,n)
y = np.sin(2*np.pi*x)
y2 = np.cos(2*np.pi*x) 
df=pd.DataFrame({'x':np.append(x, x),'y':np.append(y, y2),'class':np.append(np.repeat('sin',n),np.repeat('cos',n))})

# plot the data with the markers
# note that I put the legend=False to move it up (otherwise it was blocking the graph)
g=sns.factorplot(x="x",y="y",hue="class",palette=graycolors, data=df, linestyles=["-", "--"],markers=['o','v'], legend=False)
# placing the legend up
g.axes[0][0].legend(loc=1)
#showing graph
plt.show()

the graph