Pythonic way of slicing out part of a numpy array

Question

Suppose you have the following numpy array,

>>> x = numpy.array([0,1,2,3,4,5,6,7,8,9,10])

and you want to extract a new numpy array consisting of only the first three (3) and last four (4) elements, i.e.,

>>> y = x[something]
>>> print y
[0 1 2 7 8 9 10]

Is this possible? I know that to extract the first three numbers you simply do x[:3] and to extract the last four you do x[-4:], but is there a simple way of extracting all that in a simple slice? I know this can be done by, e.g., appending both calls,

 >>> y = numpy.append(x[:3],x[-4:])  

but I was wondering if there is some simple little trick to do it in a more direct, pythonic way, without having to reference x again (i.e., I first thought that maybe x[-4:3] could work but I realized immediately that it didn't made sense).

Answer 1

I think you should use index arrays.

indices = list(range(3))+list(range(-4,0))
y = x[indices]

You can probably drop list casts (not sure because python 3 changed the behaviour a bit). Or you could use numpy range genreators.

Edit: not sure why the downvote, cause it works:

import numpy
x = numpy.array([0,1,2,3,4,5,6,7,8,9,10])
indices = list(range(3))+list(range(-4,0))
y = x[indices]
print(y)