From: Robert Citek <robert.citek@...>
Date: 2007-12-20T09:11:46+09:00
Subject: Re: slicing in ruby

Found it: indices, which is deprecated in favor of values_at.

$ echo $(seq 1 10) | tee /dev/stderr |  ruby -lane 'print
$F.values_at(1,2,3,8,2,2).join(" -- ") '
1 2 3 4 5 6 7 8 9 10
2 -- 3 -- 4 -- 9 -- 3 -- 3

Discovered this with a brute-force search:

ruby -e 'puts [].methods.sort' |
while read name ; do
   echo == $name
   ri Array."${name}" | cat
done

Interestingly, a lot of methods didn't return anything via ri.  For example:

$ ri Array.methods
Nothing known about Array.methods

Anyone have any suggestions on a "cleaner" way to discover methods and
their docs?

Regards,
- Robert

On Dec 19, 2007 5:58 PM, Robert Citek <robert.citek@gmail.com> wrote:
>
> Is there a way to slice an array like in perl?
>
> For example, what's the ruby equivalent to doing this:
>
> $ echo $(seq 1 10) | tee /dev/stderr |  perl -lane 'print join(" -- ",
> @F[1,2,3,8,2,2]) '
> 1 2 3 4 5 6 7 8 9 10
> 2 -- 3 -- 4 -- 9 -- 3 -- 3
>
> I can get this to work:
>
> $ echo $(seq 1 10) | tee /dev/stderr |  ruby -lane 'print $F.join(" -- ") '
> 1 2 3 4 5 6 7 8 9 10
> 1 -- 2 -- 3 -- 4 -- 5 -- 6 -- 7 -- 8 -- 9 -- 10
>
> and this:
>
> $ echo $(seq 1 10) | tee /dev/stderr |  ruby -lane 'print $F[1,2].join(" -- ") '
> 1 2 3 4 5 6 7 8 9 10
> 2 -- 3
>
> but not this:
>
> $ echo $(seq 1 10) | tee /dev/stderr |  ruby -lane 'print
> $F[1,2,3,8,2,2].join(" -- ") '
> 1 2 3 4 5 6 7 8 9 10
> -e:1:in `[]': wrong number of arguments (6 for 2) (ArgumentError)
>         from -e:1
>
>
> There's probably some method I need to invoke, but which one?
>
> Regards,
> - Robert
>
>