postgres expression to select elements from array - postgresql

Question

I want to select certain elements from an array column. I know you can do it by position, but I want to filter on content. Here's my data:
table_name | column_names
---------------------+---------------------------------------------------------------
attribute_definition | {attribute_type_concept_id}
cohort_definition | {definition_type_concept_id,subject_concept_id}
condition_occurrence | {condition_concept_id,condition_source_concept_id,condition_type_concept_id}
death | {cause_concept_id,cause_source_concept_id,death_impute_concept_id,death_type_concept_id}
device_exposure | {device_concept_id,device_source_concept_id,device_type_concept_id}
drug_exposure | {dose_unit_concept_id,drug_concept_id,drug_source_concept_id,drug_type_concept_id,route_concept_id}
What I would like to say is something like:
SELECT table_name,
array_agg(SELECT colname FROM column_names WHERE colname LIKE '%type%') AS type_cols,
array_agg(SELECT colname FROM column_names WHERE colname NOT LIKE '%type%') AS other_cols
FROM mytable
GROUP BY table_name
And the result I would like would be:
table_name | type_cols | other_cols
----------------------+--------------------------------------------------------------------------------------------------------------
attribute_definition | {attribute_type_concept_id} | {}
cohort_definition | {definition_type_concept_id} | {subject_concept_id}
condition_occurrence | {condition_type_concept_id} | {condition_concept_id,condition_source_concept_id}
death | {death_type_concept_id} | {cause_concept_id,cause_source_concept_id,death_impute_concept_id}
device_exposure | {device_type_concept_id} | {device_concept_id,device_source_concept_id}
drug_exposure | {drug_type_concept_id} | {dose_unit_concept_id,drug_concept_id,drug_source_concept_id,route_concept_id}
So, I want to end up with the same number of rows but different columns. There's gotta be a simple way to do this. Why can't I find it?

Answer 1

unnest is your friend. As in:
SELECT table_name,
array(SELECT colname FROM unnest(column_names) AS colname WHERE colname LIKE '%type%') AS type_cols,
array(SELECT colname FROM unnest(column_names) AS colname WHERE colname NOT LIKE '%type%') AS other_cols
FROM mytable
GROUP BY table_name, column_names

Answer 2

Here is Dan Getz's answer again but in a self-contained statement so it's easily runnable without copying my data.
with grps as
(
with numlist as
(
select '1 - 10' as grp, generate_series(1,10) num
union
select '11 - 20', generate_series(11,20) order by 1,2
)
select grp, array_agg(num) as nums
from numlist
group by 1
)
select grp,
(select array_agg(evens) from unnest(nums) as evens where evens % 2 = 0) as evens,
(select array_agg(odds) from unnest(nums) as odds where odds % 2 != 0) as odds
from grps
group by grp, nums;
grp | evens | odds
---------+------------------+------------------
11 - 20 | {12,14,16,18,20} | {11,13,15,17,19}
1 - 10 | {2,4,6,8,10} | {1,3,5,7,9}