How to create mirror image of heatmap and megre it in Seaborn in Python?

January 4, 2022

I have data for which I can make a heatmap in the form of a triangle.

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

c = np.array([[1, np.nan, np.nan, np.nan, np.nan, np.nan],
              [-0.140898, 1, np.nan, np.nan, np.nan, np.nan],
              [0.0867051, -0.0934162, 1, np.nan, np.nan, np.nan],
              [0.117242, -0.0332325, 0.0414388, 1, np.nan, np.nan],
              [-0.120879, 0.00294446, -0.11504, -0.101007, 1, np.nan],
              [-0.696967, 0.0913504, -0.0823251, -0.0598827, 0.127752, 1]])

fig,ax = plt.subplots(1,1,sharex=True)

sns.heatmap(c,cmap='jet',
            vmin = -1,
            vmax = 1,
            ax = ax,
            annot = True,
            fmt = '.1f',
            annot_kws={"fontsize":5},
            cbar = True)

I have map looking like this:

And I would like to create a mirror image and merge it with orginal heatmap:

>Solution :

You could stack the matrix together with its mirror image. But it is unclear what you want to do with the labeling. (Use np.hstack([c[:, :0:-1], c]) if you only want the central column once).

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

c = np.array([[1, np.nan, np.nan, np.nan, np.nan, np.nan],
              [-0.140898, 1, np.nan, np.nan, np.nan, np.nan],
              [0.0867051, -0.0934162, 1, np.nan, np.nan, np.nan],
              [0.117242, -0.0332325, 0.0414388, 1, np.nan, np.nan],
              [-0.120879, 0.00294446, -0.11504, -0.101007, 1, np.nan],
              [-0.696967, 0.0913504, -0.0823251, -0.0598827, 0.127752, 1]])
labels = ['A','B','C','D','E','F']
fig, ax = plt.subplots(1, 1)
sns.heatmap(np.hstack([c[:, ::-1], c]),
            xticklabels=labels[::-1] + labels,
            yticklabels=[],
            cmap='turbo',
            vmin=-1,
            vmax=1,
            ax=ax,
            annot=True,
            fmt='.1f',
            annot_kws={"fontsize": 5},
            cbar=True)