使用python matplotlib.pyplot画矩形框

import matplotlib.patches as patches
import matplotlib.pyplot as plt

fig = plt.figure() 
ax = fig.add_subplot(111) 

# 画矩形框
currentAxis = plt.gca()  # 获取当前子图
x_rect = x_index*Tr/480
y_rect = (y_index-fft_2pow_point/2)*fr/fft_2pow_point
rect = patches.Rectangle((x_rect, y_rect), target_height*Tr/480, target_weight*fr/fft_2pow_point, linewidth=2, edgecolor=‘r‘, facecolor=‘none‘)
currentAxis.add_patch(rect)

y_grid, x_grid = np.meshgrid(np.linspace(-fr / 2, fr / 2, width + 1),
                                         np.linspace(0, Tr, 480 + 1, endpoint=False))