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#! -*- coding=utf-8 -*-
import pylab as pl
from math import log,exp,sqrt

evaluate_result="you file path"
db = []  #[score,nonclk,clk]
pos, neg = 0, 0 
with open(evaluate_result,'r') as fs:
	for line in fs:
		nonclk,clk,score = line.strip().split('\t')
		nonclk = int(nonclk)
		clk = int(clk)
		score = float(score)
		db.append([score,nonclk,clk])
		pos += clk
		neg += nonclk

db = sorted(db, key=lambda x:x[0], reverse=True)

#计算ROC坐标点
xy_arr = []
tp, fp = 0., 0.			
for i in range(len(db)):
	tp += db[i][2]
	fp += db[i][1]
	xy_arr.append([fp/neg,tp/pos])

#计算曲线下面积
auc = 0.			
prev_x = 0
for x,y in xy_arr:
	if x != prev_x:
		auc += (x - prev_x) * y
		prev_x = x

print "the auc is %s."%auc

x = [_v[0] for _v in xy_arr]
y = [_v[1] for _v in xy_arr]
pl.title("ROC curve of %s (AUC = %.4f)" % ('svm',auc))
pl.xlabel("False Positive Rate")
pl.ylabel("True Positive Rate")
pl.plot(x, y)# use pylab to plot x and y
pl.show()# show the plot on the screen