Mixing
replace elements in a 2d array
Given a 2d array
select (ARRAY[[1,2,3], [4,0,0], [7,8,9]]);
{{1,2,3},{4,0,0},{7,8,9}}
Is there a way to replace the slice at [2:2][2:] (the {{0,0}}) with values 5 and 6? array_replace replaces a specific value so I'm not sure how to approach this.
postgresql postgresql-11
asked Nov 19 '18 at 19:41
MirarisMiraris
617
add a comment |
Given a 2d array
select (ARRAY[[1,2,3], [4,0,0], [7,8,9]]);
{{1,2,3},{4,0,0},{7,8,9}}
Is there a way to replace the slice at [2:2][2:] (the {{0,0}}) with values 5 and 6? array_replace replaces a specific value so I'm not sure how to approach this.
postgresql postgresql-11
asked Nov 19 '18 at 19:41
MirarisMiraris
617
add a comment |
Given a 2d array
select (ARRAY[[1,2,3], [4,0,0], [7,8,9]]);
{{1,2,3},{4,0,0},{7,8,9}}
Is there a way to replace the slice at [2:2][2:] (the {{0,0}}) with values 5 and 6? array_replace replaces a specific value so I'm not sure how to approach this.
postgresql postgresql-11
asked Nov 19 '18 at 19:41
MirarisMiraris
617
Given a 2d array
select (ARRAY[[1,2,3], [4,0,0], [7,8,9]]);
{{1,2,3},{4,0,0},{7,8,9}}
Is there a way to replace the slice at [2:2][2:] (the {{0,0}}) with values 5 and 6? array_replace replaces a specific value so I'm not sure how to approach this.
postgresql postgresql-11
postgresql postgresql-11
asked Nov 19 '18 at 19:41
MirarisMiraris
617
asked Nov 19 '18 at 19:41
MirarisMiraris
617
edited Nov 19 '18 at 20:27
Miraris
asked Nov 19 '18 at 19:41
MirarisMiraris
617
asked Nov 19 '18 at 19:41
MirarisMiraris
617
asked Nov 19 '18 at 19:41
MirarisMiraris
617
617
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
I believe it's more readable to code a function in plpgsql. However, a pure SQL solution also exists:
select (
select array_agg(inner_array order by outer_index)
from (
select outer_index,
array_agg(
case
when outer_index = 2 and inner_index = 2 then 5
when outer_index = 2 and inner_index = 3 then 6
else item
end
order by inner_index
) inner_array
from (
select item,
1 + (n - 1) % array_length(a, 1) inner_index,
1 + (n - 1) / array_length(a, 2) outer_index
from
unnest(a) with ordinality x (item, n)
) _
group by outer_index
)_
)
from (
select (ARRAY[[1,2,3], [4,0,0], [7,8,9]]) a
)_;
answered Nov 19 '18 at 23:28
Alexey BashtanovAlexey Bashtanov
38435
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
I believe it's more readable to code a function in plpgsql. However, a pure SQL solution also exists:
select (
select array_agg(inner_array order by outer_index)
from (
select outer_index,
array_agg(
case
when outer_index = 2 and inner_index = 2 then 5
when outer_index = 2 and inner_index = 3 then 6
else item
end
order by inner_index
) inner_array
from (
select item,
1 + (n - 1) % array_length(a, 1) inner_index,
1 + (n - 1) / array_length(a, 2) outer_index
from
unnest(a) with ordinality x (item, n)
) _
group by outer_index
)_
)
from (
select (ARRAY[[1,2,3], [4,0,0], [7,8,9]]) a
)_;
answered Nov 19 '18 at 23:28
Alexey BashtanovAlexey Bashtanov
38435
add a comment |
I believe it's more readable to code a function in plpgsql. However, a pure SQL solution also exists:
select (
select array_agg(inner_array order by outer_index)
from (
select outer_index,
array_agg(
case
when outer_index = 2 and inner_index = 2 then 5
when outer_index = 2 and inner_index = 3 then 6
else item
end
order by inner_index
) inner_array
from (
select item,
1 + (n - 1) % array_length(a, 1) inner_index,
1 + (n - 1) / array_length(a, 2) outer_index
from
unnest(a) with ordinality x (item, n)
) _
group by outer_index
)_
)
from (
select (ARRAY[[1,2,3], [4,0,0], [7,8,9]]) a
)_;
answered Nov 19 '18 at 23:28
Alexey BashtanovAlexey Bashtanov
38435
add a comment |
I believe it's more readable to code a function in plpgsql. However, a pure SQL solution also exists:
select (
select array_agg(inner_array order by outer_index)
from (
select outer_index,
array_agg(
case
when outer_index = 2 and inner_index = 2 then 5
when outer_index = 2 and inner_index = 3 then 6
else item
end
order by inner_index
) inner_array
from (
select item,
1 + (n - 1) % array_length(a, 1) inner_index,
1 + (n - 1) / array_length(a, 2) outer_index
from
unnest(a) with ordinality x (item, n)
) _
group by outer_index
)_
)
from (
select (ARRAY[[1,2,3], [4,0,0], [7,8,9]]) a
)_;
answered Nov 19 '18 at 23:28
Alexey BashtanovAlexey Bashtanov
38435
I believe it's more readable to code a function in plpgsql. However, a pure SQL solution also exists:
select (
select array_agg(inner_array order by outer_index)
from (
select outer_index,
array_agg(
case
when outer_index = 2 and inner_index = 2 then 5
when outer_index = 2 and inner_index = 3 then 6
else item
end
order by inner_index
) inner_array
from (
select item,
1 + (n - 1) % array_length(a, 1) inner_index,
1 + (n - 1) / array_length(a, 2) outer_index
from
unnest(a) with ordinality x (item, n)
) _
group by outer_index
)_
)
from (
select (ARRAY[[1,2,3], [4,0,0], [7,8,9]]) a
)_;
answered Nov 19 '18 at 23:28
Alexey BashtanovAlexey Bashtanov
38435
answered Nov 19 '18 at 23:28
Alexey BashtanovAlexey Bashtanov
38435
answered Nov 19 '18 at 23:28
Alexey BashtanovAlexey Bashtanov
38435
answered Nov 19 '18 at 23:28
Alexey BashtanovAlexey Bashtanov
38435
38435
add a comment |
add a comment |
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