How can I split list from matrix in python?

con =  np.array([[   0,    0,    0,    0,  500,    0,    0,    0,    0,    0,    0,
                     0,    0,    0,    0,    0,  500,    0],
                 [   0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
                     0,    0,    0,    0,    0,    0,    0],
                 [   0, 1000,    0,    0,    0,    0,    0,    0,    0,    0,    0,
                   500,    0,    0,    0,    0,    0,    0],
                 [   0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,
                     0,    0,    0,    0,    0,    0,    0]])

For this 4×18 matrix: In each row, I want to keep the value that more than 0 such as in first row 500 and 500

This is my current matrix:

newArr5=[]
for j in range (4):
    for i in range (18):
        if con[j][i] > 0:
            newArr5.append(con[j][i])

But the output shows:

[500, 500, 1000, 500]

I am looking find the way to split list. When the second and fourth row, there is no grater than zero value, it should be [0]:

[[500, 500], [0], [1000,500], [0]]

>Solution :

You need to create a new result list for each row, not use the same list for the entire matrix.

newArr5 = []
for row in con:
    above_zero = [x for x in row if x > 0] or [0]
    newArr5.append(above_zero)

Or as a single list comprehension:

newArr5 = [[x for x in row if x > 0] or [0] for row in con]