How to reverse colorscales in seaborn heatmap

Question

For diverging values seaborn by default seems to show big numbers in warm tone (orange) and small numbers in cold tone (blue).

If I need to switch color to opposite, to show big numbers in blue and small in orange, how to do so?

I've searched but haven't found a way.

sns.heatmap(flights, center=flights.loc["January", 1955])

Answer 1

You can reverse all of the matplotlib colormaps by appending _r to the name, i.e., plt.cm.coolwarm vs plt.cm.coolwarm_r.

I believe seaborn uses a cubehelix colormap by default.

So you'd do:

from matplotlib import pyplot
import seaborn as sns

colormap = pyplot.cm.cubehelix_r
flights = sns.load_dataset('flights').pivot("month", "year", "passengers")
sns.heatmap(flights, cmap=colormap)

Answer 2

There is no need to build a separate reverse function for heatmap.

Just use cmap = 'magma_r'. The default setting is magma and thus we just append the '_r' for reverse.