title: How to randomly sample a matrix in python?
body: <p>I have a relatively large array, e.g. 200 x 1000.The matrix is a sparse matrix where elements are can be considered weights. The weights range from 0 to 500.  I would like to generate a new array of the same size, 200x1000, where N of the elements of the new array are random integers {0,1}. The probability of an element in the new matrix being 0 or 1 is proportional to the weights from the original array - the higher the weight the higher the probability of 1 versus 0. </p>
  
  <p>Stated another way: I would like to generate a zero matrix of size 200x1000 and then randomly choose N elements to flip to 1 based on a 200x1000 matrix of weights.  </p>