How to find the minimum value in a numpy matrix?

Hey this is a quick and easy question... How would i find the minimum value of this matrix, excluding 0? As in, 8

arr = numpy.array([[  0.,  56.,  20.,  44.],
                   [ 68.,   0.,  56.,   8.],
                   [ 32.,  56.,   0.,  44.],
                   [ 68.,  20.,  56.,   0.]])

Solution

As you're using numpy, you could use

arr[arr>0].min()

for the case you posted. but if your array could have negative values, then you should use

arr[arr != 0].min()