Scan over every other element of a tensor variable in Theano

Question

it should produce something like:

input = [1,2,3,4,5,6]
output = scan_every_other(lambda x:x, input)
// output should be [1,3,5]

I have briefly read the theano.scan tutorial but I didn't find what I'm looking for. Thank you.:)

Answer 1

You don't need to use theano.scan. Just use ordinary index/slice notation as in numpy:

In numpy, if

input = [1,2,3,4,5,6]

then

print input[::2]

will display

[1, 3, 5]

In Theano, this can be achieved by doing the same thing:

import theano
import theano.tensor as tt
input = tt.vector()
f = theano.function([input], input[::2])
print f([1,2,3,4,5,6])