code: def sparse_to_matrix(sparse):
      
  
      sparse = np.asanyarray(sparse, dtype=np.int)
      if not util.is_shape(sparse, (-1, 3)):
          raise ValueError('sparse must be (n,3)!')
  
      shape = sparse.max(axis=0) + 1
      matrix = np.zeros(np.product(shape), dtype=np.bool)
      multiplier = np.array([np.product(shape[1:]), shape[2], 1])
  
      index = (sparse * multiplier).sum(axis=1)
      matrix[index] = True
  
      dense = matrix.reshape(shape)
      return dense
docs: Take a sparse (n,3) list of integer indexes of filled cells,
      turn it into a dense (m,o,p) matrix.
  
      Parameters
      -----------
      sparse: (n,3) int, index of filled cells
  
      Returns
      ------------
      dense: (m,o,p) bool, matrix of filled cells