Re: Array operator "sum array values"

["Pavel Stehule" <pavel(dot)stehule(at)gmail(dot)com>]

Hello

On 31/03/2008, Scara Maccai <m_lists(at)yahoo(dot)it> wrote:
> Hi,
>
>  is there a syntax that sums the values of an array?
>
>  That is, having an array like
>
>  {1,3,8},{5,6,7}
>
>  something like
>
>  select arr[1:2][2:3]
>
>  gives
>
>  {1,3},{6,7}
>
>
>  ; what I'd like is:
>
>  select arr[1$2][2$3]
>
>  gives:
>
>  17 (that is, 1+3 + 6+7)
>
>  If there is no such operator, would it be complicated adding it to postgres?
>  I mean: is the "[:]" operator an internal thing (the parser "knows" about it) or is it just like any other operators that can be added ?
>
>

create or replace function sum_elements(anyarray)
returns anyelement as $$
select sum($1[i])
   from generate_series(array_lower($1,1),
                                       array_upper($1,1)) g(i);
$$ language sql immutable;

select sum_elements(array[1,2,3]); --> 6

Regards
Pavel Stehule
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