I am trying to extract several values at once from an array but I can’t seem to find a way to do it in a one-liner in Numpy.
Simply put, considering an array:
a = numpy.arange(10)
> array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])
I would like to be able to extract, say, 2 values, skip the next 2, extract the 2 following values etc. This would result in:
array([0, 1, 4, 5, 8, 9])
This is an example but I am ideally looking for a way to extract x values and skip y others.
I thought this could be done with slicing, doing something like:
a[:2:2]
but it only returns 0, which is the expected behavior.
I know I could obtain the expected result by combining several slicing operations (similarly to Numpy Array Slicing) but I was wondering if I was not missing some numpy feature.
>Solution :
You can use a modulo operator:
x = 2 # keep
y = 2 # skip
out = a[np.arange(a.shape[0])%(x+y)<x]
Output: array([0, 1, 4, 5, 8, 9])
Output with x = 2 ; y = 3:
array([0, 1, 5, 6])