import numpy as np
import matplotlib.pyplot as plt


def main():
	# 设置x和y的坐标范围
  x=np.arange(-2,2,0.01)
  y=np.arange(-2,2,0.01)
  # 转化为网格
  x,y=np.meshgrid(x,y)
  z=np.power(x,2)+np.power(y,2)-1
  plt.contour(x,y,z,0)
  plt.show()


main()
绘制的时候要保证x，y，z的维度相同