I have got a function with a reg expr to split chemical formulas e.g. H2O -> H2 O.
CREATE OR REPLACE FUNCTION daimon.text2sumformula(text) RETURNS text[] AS $$ select array_agg(i::text) as e from ( select unnest( regexp_matches( $1, '[0-9]*[A-Z][a-z]?\d*|\((?:[^()]*(?:\(.*\))?[^()]*)+\)\d+', 'g') ) ) i; $$ LANGUAGE SQL IMMUTABLE;
For H2O I get an array with {(H2),(O)} How I can return the inner elements as text, I would like to get {H2,O} without round brackets?
like this?
postgres=# select array_agg(i[1]) as e from regexp_matches( 'H2O', '[0-9]*[A-Z][a-z]?\d*|\((?:[^()]*(?:\(.*\))?[^()]*)+\)\d+', 'g') t(i); e -------- {H2,O} (1 row)