ROC test

draw_roc2.py

# -*- coding: utf-8 -*-
"""
Created on 04/06/16 14:08:31

ROC曲線を「はじめてのパターン認識」(P.34) に基づいて描く

@author: Satoshi MURASHIGE
"""

import sys
import numpy as np
import matplotlib.pyplot as plt

# 識別器が出した得点
data_scores = np.array([0.9,
                        0.8,
                        0.7,
                        0.55,
                        0.45,
                        0.4,
                        0.34,
                        0.3,
                        0.2,
                        0.1])
# 事実
data_labels = np.array([1,
                       1,
                       0,
                       1,
                       1,
                       0,
                       0,
                       1,
                       0,
                       0])

# 閾値を変えながら識別器に予測させる
TP = np.zeros(data_scores.shape[0] + 1)
FP = np.zeros(data_scores.shape[0] + 1)
for k, th in enumerate(np.concatenate(([100], data_scores))):
    # 識別器の予測
    predict = np.float32(data_scores >= th)
    TP[k] = np.count_nonzero(data_labels[data_labels == predict]) / np.count_nonzero(data_labels)
    FP[k] = np.count_nonzero(1 - data_labels[data_labels != predict]) / np.count_nonzero(1 - data_labels)


plt.xlim(0, 1)
plt.ylim(0, 1)
plt.plot(FP, TP, linewidth=5)
plt.plot(FP, TP, 'ro', markersize=10)
plt.show()