old_contents: import matplotlib.pyplot as plt
  
  x = np.linspace(-10, 10, 40)
  y = np.linspace(-15, 15, 60)
  Y,X = np.meshgrid(y,x)
  noise = np.random.randn(*X.shape) * 10
  data = X**2 + Y**2 + noise
  data = np.ma.array(data, mask=((X**2 + Y**2) < 0.4))
  
  data_filt = gaussian_filter(x, y, data, 4, 4)
  
  plt.subplot(1, 2, 1)
  plt.imshow(data.T, interpolation='nearest',
      extent=(x.min(), x.max(), y.min(), y.max()))
  
  plt.subplot(1, 2, 2)
  plt.imshow(data_filt.T, interpolation='nearest',
      extent=(x.min(), x.max(), y.min(), y.max()))
  
  plt.show()
  
new_contents: import matplotlib.pyplot as plt
  import numpy as np
  from metpy.tools import gaussian_filter
  
  x = np.linspace(-10, 10, 40)
  y = np.linspace(-15, 15, 60)
  Y,X = np.meshgrid(y,x)
  noise = np.random.randn(*X.shape) * 10
  data = X**2 + Y**2 + noise
  data = np.ma.array(data, mask=((X**2 + Y**2) < 0.4))
  
  data_filt = gaussian_filter(x, y, data, 4, 4)
  
  plt.subplot(1, 2, 1)
  plt.imshow(data.T, interpolation='nearest',
      extent=(x.min(), x.max(), y.min(), y.max()))
  
  plt.subplot(1, 2, 2)
  plt.imshow(data_filt.T, interpolation='nearest',
      extent=(x.min(), x.max(), y.min(), y.max()))
  
  plt.show()
  
subject: Add some missing imports.