For a gnerally binary operator I would personally do something like
x = 1:5
f = +
map(f,x[1:end-1],x[2:end])
This pattern has obvious generalizations to the n-ary case. In clojure data
analysis you see a lot composition of the map and partition/partitionby/etc
functions (the partition* functions in clojure break up sequences into a
sequence of windows). I know julia is not clojure but I think the window
and map pattern accurately reflects the way many scientific programmers
think about this type of operation, which is relatively common across a
number of domains. As such I think it would be nice to establish some kind
of terse but idiomatic way of writing these thing in julia (@Evan thanks
for the question!).
Leaving implementation details aside I'll start the discussion by
advocating for something like
mapnwise{N,T}(f::Function,n::Int,x::AbstractArray{N,T}) = ...
There could also be an argument for other windowing schemes, but this would
be a start.
where the signature of f is
On Saturday, February 7, 2015 at 1:19:39 PM UTC+1, Evan Pu wrote:
>
> say I want to compute a pair-wise diff for all the elements in the array.
> input: [1, 2, 4, 7, 8]
> output: [1, 2, 3, 1]
>
> is there some kind of "beautiful" way of doing it? i.e. w/o using a for
> loop nor using explicit indecies
>
