b[:] = b .+ 5
has the behavior that you want. However, it creates a copy, does the
addition, then copies the result back into b.
So, looping (aka devectorizing) would generally be faster. For simple
expressions like these, though, the Devectorize.jl package should allow you
to write
@devec b[:] = b .+ 5
It then rewrites the expression as a loop. It isn't able to recognize some
expressions, though (especially complex ones), so YMMV.
(Actually, it may not work with ".+", since that is a relatively new change
in the language. If you check and it doesn't, try submitting a github
issue, or just report back here.)
Cheers! Kevin
On Thursday, May 1, 2014, Kaj Wiik <kaj.w...@gmail.com> wrote:
> OK, thanks, makes sense. But how to change the original instance, is
> looping the only way?
>
> On Thursday, May 1, 2014 3:12:51 PM UTC+3, Freddy Chua wrote:
>
> b = b .+ 5
>
> creates a new instance of an array, so the original array pointed to by
> "b" is not changed at all.
>
>
>
> On Thursday, May 1, 2014 7:39:14 PM UTC+8, Kaj Wiik wrote:
>
> As a new user I was surprised that even if you change the value of
> function arguments (inside the function) the changes are not always visible
> outside but in some cases they are.
>
> Here's an example:
>
> function vappu!(a,b)
> a[3]=100
> b = b .+ 5
> (a,b)
> end
>
> c = [1:5]
> d = [1:5]
>
> vappu!(c,d)
> ([1,2,100,4,5],[6,7,8,9,10])
>
> c
> 5-element Array{Int64,1}:
> 1
> 2
> 100
> 4
> 5
> d
> 5-element Array{Int64,1}:
> 1
> 2
> 3
> 4
> 5
>
>
