Remove lines separating cells in seaborn heatmap when saved as pdf

Question

I would like to remove the lines that separate the cells in a saved pdf. I tried setting the linewidth=0.0, but the lines are still showing.

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

data = pd.DataFrame(np.arange(10*10).reshape(10,10))
fig, ax = plt.subplots()
ax = sns.heatmap(data,linewidths=0.0)
fig.savefig('stackoverflow_lines.pdf')

The image is a screen capture of the resulting pdf.

Answer 1

This is an issue only when saving to PDF files, if you use something like a PNG then it will work fine. A Github Issue has been raised here with the developers.

In the meantime, the developer mwaskom has found a fix where you can add rasterized=True to the seaborn.heatmap function which fixes the issue. Your code then becomes:

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

data = pd.DataFrame(np.arange(10*10).reshape(10,10))
fig, ax = plt.subplots()
ax = sns.heatmap(data,linewidths=0.0, rasterized=True)
fig.savefig('stackoverflow_lines.pdf')