matplotlib/seaborn: first and last row cut in half of heatmap plot

Question

When plotting heatmaps with seaborn (and correlation matrices with matplotlib) the first and the last row is cut in halve. This happens also when I run this minimal code exa

Answer 1

matplotlib 3.1.2 is out - It is available in the Anaconda cloud via conda-forge but I was not able to install it via conda install. The manual alternative worked: Download matplotlib 3.1.2 from github and install via pip

 % curl https://codeload.github.com/matplotlib/matplotlib/tar.gz/v3.1.2 --output matplotlib-3.1.2.tar.gz
 % pip install matplotlib-3.1.2.tar.gz

Answer 2

Worked for me:

b, t = plt.ylim()
b += 0.5
t -= 0.5
custom_ylim = (b, t)
plt.setp(axes, ylim=custom_ylim)

Answer 3

Unfortunately matplotlib 3.1.1 broke seaborn heatmaps; and in general inverted axes with fixed ticks.
This is fixed in the current development version; you may hence

• revert to matplotlib 3.1.0
• use matplotlib 3.1.2 or higher
• set the heatmap limits manually (ax.set_ylim(bottom, top) # set the ylim to bottom, top)

Answer 4

I solved this problem with the following code:

Answer 5

rustyDev is right about conda-forge, but I did not need to do a manual pip install from a github download. For me, on Windows, it worked directly. And the plots are all nice again.

https://anaconda.org/conda-forge/matplotlib

conda install -c conda-forge matplotlib

optional points, not needed for the answer:

Afterwards, I tried other steps, but they are not needed: In conda prompt: conda search matplotlib --info showed no new version info, the most recent info was for 3.1.1. Thus I tried pip using pip install matplotlib==3.1.2 But pip says "Requirement already satisfied"

Then getting the version according to medium.com/@rakshithvasudev/… python - import matplotlib - matplotlib.__version__ shows that 3.1.2 was successfully installed

Btw, I had this error directly after updating Spyder to v4.0.0. The error was in a plot of a confusion matrix. This was mentioned already some months ago. stackoverflow.com/questions/57225685/… which is already linked to this seaborn question.