[Numpy-discussion] median filtering question -- masked arrays

Does anyone have a hint for applying a median filter to a masked 2D array in numarray? I've been using the kludge of extracting a normal array with the masked data replaced by the overall median of the array and median filtering that (with the appropriate nd_image method). But this is a crude approximation and I'd like to do better -- preferably without coding my own median filter in C. -- Russell