Обсуждение: How to remove n-first elements from array?
Hi,
I have array for example
do $$
declare
v_arr integer[] := array[1, 2, 3, 4, 5];
begin
end;
$$
I want to remove 2 first element and get array with non-changed indexes
(subscript)
new array := '[3:5]={3, 4, 5}'::integer[]
It is possible in pl/pgsql?
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I found solution
do $$
declare
v_array integer[] := array[1,2,3,4,5];
v_array2 integer[];
v_delete_elements integer :=2;
v_new_index integer;
begin
v_new_index := array_lower(v_array, 1) + v_delete_elements;
v_array2 := array_fill(v_array[v_new_index], ARRAY[1], ARRAY[v_new_index])
|| v_array[v_new_index+1:array_upper(v_array, 1)];
raise notice '%', v_array2;
end;
$$
NOTICE: [3:5]={3,4,5}
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On Mon, Dec 17, 2012 at 3:27 AM, aasat <satriani@veranet.pl> wrote:
> I found solution
>
> do $$
> declare
> v_array integer[] := array[1,2,3,4,5];
> v_array2 integer[];
> v_delete_elements integer :=2;
> v_new_index integer;
> begin
> v_new_index := array_lower(v_array, 1) + v_delete_elements;
>
> v_array2 := array_fill(v_array[v_new_index], ARRAY[1], ARRAY[v_new_index])
> || v_array[v_new_index+1:array_upper(v_array, 1)];
> raise notice '%', v_array2;
> end;
> $$
>
> NOTICE: [3:5]={3,4,5}
here's a solution that's a bit more general:
create or replace function remove_front(a anyarray, nkeep int) returns
anyarray as
$$
select a[array_upper(a, 1) - (nkeep - 1):array_upper(a, 1)];
$$ language sql immutable;
merlin
Thank you!
More general, but that lose bounds of array
Result is
NOTICE: {3,4,5}
but I want
NOTICE: [3:5]{3,4,5}
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On Mon, Dec 17, 2012 at 9:02 AM, aasat <satriani@veranet.pl> wrote:
> Thank you!
>
> More general, but that lose bounds of array
>
> Result is
>
> NOTICE: {3,4,5}
>
> but I want
>
> NOTICE: [3:5]{3,4,5}
why do you want that? IMNSHO custom lower bounds arrays is a misfeature.
merlin
I use it for page hits aggregations, It's very fast, my arrays contains no more than 1000 elements (array_upper-array_lower <=1000) and array bounds is mapped to time. -- View this message in context: http://postgresql.1045698.n5.nabble.com/How-to-remove-n-first-elements-from-array-tp5736765p5736933.html Sent from the PostgreSQL - general mailing list archive at Nabble.com.