from sklearn.datasets import load_digits
from sklearn.model_selection import train_test_split
from sklearn.naive_bayes import GaussianNB
X, y = load_digits(return_X_y=True)
X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.33)
nb = GaussianNB()
nb.fit(X_train, y_train)
predicted_probas = nb.predict_proba(X_test)
# The magic happens here
import matplotlib.pyplot as plt
import scikitplot as skplt
skplt.metrics.plot_roc(y_test, predicted_probas)
plt.show()

图：ROC曲线

P-R曲线就是精确率precision vs 召回率recall 曲线，以recall作为横坐标轴，precision作为纵坐标轴。首先解释一下精确率和召回率。

import matplotlib.pyplot as plt
from sklearn.naive_bayes import GaussianNB
from sklearn.datasets import load_digits as load_data
import scikitplot as skplt
# Load dataset
X, y = load_data(return_X_y=True)
# Create classifier instance then fit
nb = GaussianNB()
nb.fit(X,y)
# Get predicted probabilities
y_probas = nb.predict_proba(X)
skplt.metrics.plot_precision_recall_curve(y, y_probas, cmap='nipy_spectral')
plt.show()

from sklearn.ensemble import RandomForestClassifier
from sklearn.datasets import load_digits as load_data
from sklearn.model_selection import cross_val_predict
import matplotlib.pyplot as plt
import scikitplot as skplt
X, y = load_data(return_X_y=True)
# Create an instance of the RandomForestClassifier
classifier = RandomForestClassifier()
# Perform predictions
predictions = cross_val_predict(classifier, X, y)
plot = skplt.metrics.plot_confusion_matrix(y, predictions, normalize=True)
plt.show()