from sklearn.datasets import fetch_lfw_people
from sklearn.decomposition import PCA

people = fetch_lfw_people(min_faces_per_person=20, resize=0.7)

pca = PCA(n_components=100).fit(people.data)
pca.score_samples(people.data)

yields

/home/andy/checkout/scikit-learn/sklearn/decomposition/base.py:75: RuntimeWarning: divide by zero encountered in true_divide precision.flat[::len(precision) + 1] += 1. / exp_var_diff

and then a

ValueError: array must not contain infs or NaNs