Get all except first and last n elements of a numpy array

Question

I want to get all but the first and last n elements from an array, can I do this while keeping consistent behaviour for n=0 without using an if statement? (Python 2.7). This does what I want, but falls apart if nCut=0:

nCut = 3
newArray = oldArray[nCut:-nCut]

This is closer, but doesn't include the last element (and is also really just a slightly hidden if statement)

newArray = oldArray[nCut:-nCut-1*(nCut<1)]

I have to do this to a bunch of arrays I'm loading from files, so not having a big ugly doubled up if for the n=0 case would be nice.

Answer 1

Add len(oldArray) yourself instead of counting on the slicing implementation to do it for you:

newArray = oldArray[nCut:len(oldArray)-nCut]

You can also use -nCut or None to use None as the endpoint if it would otherwise be 0:

newArray = oldArray[nCut:-nCut or None]

None is what a slice endpoint is set to if you don't write one in, so this is equivalent to oldArray[nCut:] when nCut is 0. This is less immediately understandable, but also less verbose. It may be a better choice in cases of multidimensional slicing, or if the expression for the array is more complex than just oldArray.