Pretty confusion matrix visualisation with matplotlib

Question

I'm wondering if there are some templates for viewing confusion matrices in matplotlib with a similar rendering, of which I ignore the specific nomenclature.

Answer 1

I have tried doing something similar with your fig 2. Here is my code using hand written digits data.

import numpy as np
from scipy import ndimage
from matplotlib import pyplot as plt
from sklearn import manifold, datasets
from scipy.spatial.distance import pdist, squareform
from scipy.cluster.hierarchy import leaves_list, linkage

def get_small_Xy(X, y, n=8):
    X = np.vstack([X[y==e][0:n] for e in np.unique(y)])
    y = np.hstack([[e]*n for e in np.unique(y)])
    return X, y

# Load digit data
X_, y_ = datasets.load_digits(return_X_y=True)

# get a small set of data
X, y = get_small_Xy(X_, y_)

# Get similarity matrix
D = 1-squareform(pdist(X, metric='cosine'))

Z = linkage(D, method='ward')
ind = leaves_list(Z)
D = D[ind, :]
D = D[:, ind]

# labels and colors related
lbs = np.array([i if i==j else 10 for i in y for j in y])
colors = np.array(['C{}'.format(i) for i in range(10)]+['gray'])
colors[7] = '#413c39'
c = colors[lbs]


font1 = {'family': 'Arial',
        'weight': 'normal',
        'size': 8,
        }

fig, ax = plt.subplots(1, 1, figsize=(10, 10))

n = np.product(X.shape[0])
xx, yy = np.meshgrid(range(n), range(n))
xy = np.stack([xx.ravel(), yy.ravel()]).T


ax.scatter(xy[:, 0], xy[:, 1], s=D**4*30, fc=c, ec=None, alpha=0.8)
ax.set_xlim(-1, n)
ax.set_ylim(n, -1)

ax.tick_params(top=False, bottom=False, left=False, right=False, labelleft=False, labelbottom=False)

# place text
for i, e in enumerate(y):
    ax.text(-1.2, i, e, ha='right', va='center', fontdict=font1, c=colors[e])
    
for i, e in enumerate(y):
    ax.text(i, -1, e, ha='center', va='bottom', fontdict=font1, c=colors[e])
    
# draw lines
for e in np.where(np.diff(y))[0]:
    ax.axhline(e+0.5, color='gray', lw=0.5, alpha=0.8)
    ax.axvline(e+0.5, color='gray', lw=0.5, alpha=0.8)

One issue is the alpha of all points, which seems not to possible to set with different values with plot scatters in one run.