I have a 2d array that takes this kind of form:

```
[5643, 22, 0.67, [1.00, 0.05, -0.044....]]
[6733, 12, -0.44, [0.00, 1.00, -0.08...]] 

```

so it has dimensions ~13k x 4 but the 4th column of every row is itself an array

what I’d like to do is subset this array such that I only keep the rows for which the yth element of the 4th column is greater than 0

my current approach has been this:

```
mask = [x[y] > 0 for x in array[:,3]]

new_array = array[mask]

```

Is there a faster way to do this?