File Content: plot_face_compress.py #!/usr/bin/python # -*- coding: utf-8 -*- """ ========================================================= Vector Quantization Example ========================================================= Face, a 1024 x 768 size image of a raccoon face, is used here to illustrate how `k`-means is used for vector quantization. """ print(__doc__) # Code source: Gaël Varoquaux # Modified for documentation by Jaques Grobler # License: BSD 3 clause import numpy as np import scipy as sp import matplotlib.pyplot as plt from sklearn import cluster from sklearn.utils.testing import SkipTest from sklearn.utils.fixes import sp_version if sp_version < (0, 12): raise SkipTest("Skipping because SciPy version earlier than 0.12.0 and " "thus does not include the scipy.misc.face() image.") try: face = sp.face(gray=True) except AttributeError: # Newer versions of scipy have face in misc from scipy import misc face = misc.face(gray=True) n_clusters = 5 np.random.seed(0) X = face.reshape((-1, 1)) # We need an (n_sample, n_feature) array k_means = cluster.KMeans(n_clusters=n_clusters, n_init=4) k_means.fit(X) values = k_means.cluster_centers_.squeeze() labels = k_means.labels_ # create an array from labels and values face_compressed = np.choose(labels, values) face_compressed.shape = face.shape vmin = face.min() vmax = face.max() # original face plt.figure(1, figsize=(3, 2.2)) plt.imshow(face, cmap=plt.cm.gray, vmin=vmin, vmax=256) # compressed face plt.figure(2, figsize=(3, 2.2)) plt.imshow(face_compressed, cmap=plt.cm.gray, vmin=vmin, vmax=vmax) # equal bins face regular_values = np.linspace(0, 256, n_clusters + 1) regular_labels = np.searchsorted(regular_values, face) - 1 regular_values = .5 * (regular_values[1:] + regular_values[:-1]) # mean regular_face = np.choose(regular_labels.ravel(), regular_values, mode="clip") regular_face.shape = face.shape plt.figure(3, figsize=(3, 2.2)) plt.imshow(regular_face, cmap=plt.cm.gray, vmin=vmin, vmax=vmax) # histogram plt.figure(4, figsize=(3, 2.2)) plt.clf() plt.axes([.01, .01, .98, .98]) plt.hist(X, bins=256, color='.5', edgecolor='.5') plt.yticks(()) plt.xticks(regular_values) values = np.sort(values) for center_1, center_2 in zip(values[:-1], values[1:]): plt.axvline(.5 * (center_1 + center_2), color='b') for center_1, center_2 in zip(regular_values[:-1], regular_values[1:]): plt.axvline(.5 * (center_1 + center_2), color='b', linestyle='--') plt.show() Submit