python 自己实现绘制roc曲线

1. auc 的意义及计算公式

https://blog.csdn.net/qq_22238533/article/details/78666436

2. roc的绘制代码

def roc_draw(predict, ground_truth):
    nums = len(predict)
    
    x, y = 1, 1
    
    index = np.argsort(predict)
    ground = ground_truth[index]
    
    x_step = 1.0/(nums-sum(ground_truth)) # 负样本步长
    y_step = 1./sum(ground_truth)
    
    res_x = []
    res_y = []
    
    for i in range(nums):
        if ground[i] == 1:
            y -= y_step
        else:
            x -= x_step
    
        res_x.append(x)
        res_y.append(y)
    return res_x, res_y

import numpy as np

predict = np.arange(0,1,0.01)      #生成间隔为0.01的预测阈值  
ground_truth = np.random.randint(0,2,100)

import matplotlib.pyplot as plt

x, y = roc_draw(predict, ground_truth)
plt.plot(x,y)

 

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