Changing the rotation of tick labels in Seaborn heatmap

Solution 1:

seaborn uses matplotlib internally, as such you can use matplotlib functions to modify your plots. I've modified the code below to use the plt.yticks function to set rotation=0 which fixes the issue.

import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
import seaborn as sns


data = pd.DataFrame(np.random.normal(size=40*40).reshape(40,40))

yticks = data.index
keptticks = yticks[::int(len(yticks)/10)]
yticks = ['' for y in yticks]
yticks[::int(len(yticks)/10)] = keptticks

xticks = data.columns
keptticks = xticks[::int(len(xticks)/10)]
xticks = ['' for y in xticks]
xticks[::int(len(xticks)/10)] = keptticks

sns.heatmap(data,linewidth=0,yticklabels=yticks,xticklabels=xticks)

# This sets the yticks "upright" with 0, as opposed to sideways with 90.
plt.yticks(rotation=0) 

plt.show()

Solution 2:

You can also call the methods of heatmap object:

    g = sns.heatmap(data,linewidth=0,yticklabels=yticks,xticklabels=xticks)
    g.set_yticklabels(g.get_yticklabels(), rotation = 0, fontsize = 8)

I am not sure why this isn't in the documentation for sns.heatmap, but the same methods are described here: http://seaborn.pydata.org/generated/seaborn.FacetGrid.html

I believe these methods are available to every seaborn plot object but couldn't find a general API for that.