使用bob python包在DET曲线中绘制EER点

Question

示例代码：

>>> from matplotlib import pyplot
>>> import bob.measure
>>> positives = np.random.normal(1,1,100)
>>> negatives = np.random.normal(-1,1,100)
>>> # we assume you have your negatives and positives already split
>>> npoints = 100
>>> bob.measure.plot.det(negatives, positives, npoints, color=(0,0,0), linestyle='-', label='test') 
>>> bob.measure.plot.det_axis([0.01, 40, 0.01, 40]) 
>>> pyplot.xlabel('FAR (%)') 
>>> pyplot.ylabel('FRR (%)') 
>>> pyplot.grid(True)
>>> pyplot.show() 

此代码返回以下图像：

以下函数计算EER：

eer1 = bob.measure.eer_rocch(negatives, positives)

我想包括这个交叉点＆＃34;点＆＃34;进入曲线。 我尝试过：

>>> from matplotlib import pyplot
>>> import bob.measure
>>> positives = np.random.normal(1,1,100)
>>> negatives = np.random.normal(-1,1,100)
>>> # we assume you have your negatives and positives already split
>>> npoints = 100
>>> bob.measure.plot.det(negatives, positives, npoints, color=(0,0,0), linestyle='-', label='test') 
>>> bob.measure.plot.det_axis([0.01, 40, 0.01, 40]) 
>>> pyplot.plot(eer1,eer1) 
>>> pyplot.xlabel('FAR (%)') 
>>> pyplot.ylabel('FRR (%)') 
>>> pyplot.grid(True)
>>> pyplot.show() 

没有成功。 我想得到一个数字，如下例所示：

Answer 1

此问题已在 https://gitlab.idiap.ch/bob/bob.measure/-/merge_requests/95 中修复并包含在 bob.measure 的新版本中。为确保该点落在绘图上，请显着增加点数。

from matplotlib import pyplot
import bob.measure
import numpy as np
npoints = 1000 # use a large number here
positives = np.random.normal(1,1,100)
negatives = np.random.normal(-1,1,100)
bob.measure.plot.det(negatives, positives, npoints, color=(0,0,0), linestyle='-', label='test') 
bob.measure.plot.det_axis([0.01, 40, 0.01, 40])
eer1 = bob.measure.eer(negatives, positives)
# DET plots are in log scale, use ppndf to convert the point
eer2 = bob.measure.ppndf(eer1)
pyplot.plot(eer2, eer2, "o", label=f"EER={eer1*100}%")
pyplot.xlabel('FAR (%)') 
pyplot.ylabel('FRR (%)') 
pyplot.grid(True)
pyplot.legend()
pyplot.show()