numpy实现NMS

import numpy as np
import matplotlib.pyplot as plt


def py_cpu_nms(dets, thresh):

   x1 = dets[:, 0]
   y1 = dets[:, 1]
   x2 = dets[:, 2]
   y2 = dets[:, 3]
   scores = dets[:, 4]
   areas = (x2-x1+1)*(y2-y1+1)
   res = []
   index = scores.argsort()[::-1]
   while index.size>0:
       i = index[0]
       res.append(i)
       x11 = np.maximum(x1[i],x1[index[1:]])
       y11 = np.maximum(y1[i], y1[index[1:]])
       x22 = np.minimum(x2[i],x2[index[1:]])
       y22 = np.minimum(y2[i],y2[index[1:]])

       w = np.maximum(0,x22-x11+1)
       h = np.maximum(0,y22-y11+1)

       overlaps = w * h
       iou = overlaps/(areas[i]+areas[index[1:]]-overlaps)

       idx = np.where(iou<=thresh)[0]
       index = index[idx+1]
   print(res)
   return res

def plot_boxs(box,c):
    x1 = box[:, 0]
    y1 = box[:, 1]
    x2 = box[:, 2]
    y2 = box[:, 3]

    plt.plot([x1,x2],[y1,y1],c)
    plt.plot([x1,x2],[y2,y2],c)
    plt.plot([x1,x1],[y1,y2],c)
    plt.plot([x2,x2],[y1,y2],c)
    
if __name__ == '__main__':
    boxes = np.array([[100, 100, 210, 210, 0.72],
                      [250, 250, 420, 420, 0.8],
                      [220, 220, 320, 330, 0.92],
                      [230, 240, 325, 330, 0.81],
                      [220, 230, 315, 340, 0.9]])
    plt.figure()
    ax1 = plt.subplot(121)
    ax2 = plt.subplot(122)
    plt.sca(ax1)
    plot_boxs(boxes,'k')

    res = py_cpu_nms(boxes,0.7)
    plt.sca(ax2)
    plot_boxs(boxes[res],'r')
    plt.show()

标签：index,NMS,实现,x2,y1,np,dets,y2,numpy
来源： https://blog.csdn.net/EMIvv/article/details/122377369