Heatmap linewidths=0.0 not working when saving as PDF.

A question on Stack Overflow was recently asked here where using sns.heatmap(data,linewidths=0.0) and saving the plot as a PDF doesn’t seem to work as there is still a gap between each “cell”.

The code below is from the question (in case the question is deleted, etc) and reproduces the issue

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_pdf.pdf')

If a PNG is used then it seems to work fine, i.e. the linewidth is zero and there are no gaps in between cells.

System details:

• Python 3.4.2
• matplotlib 1.4.2
• seaborn 0.5.0

Edited: had the wrong SO question link --_

[mwaskom]

OK figured it out, you need to pass rasterized=True to heatmap (which gets passed down to plt.pcolormesh).

[mwaskom]

Gonna close this as there’s really nothing seaborn could do to avoid these lines. See here for a bit more info about why this is an issue with the pdf rendering, and not the drawing per se.