How to do sorting on irregular Alphanumeric data in postgres sql

Question

I have the following sample data for a particular column symbol for sample table.

(Update:) The data is not in a regular pattern. Number may occur at any place in be

Answer 1

CREATE OR REPLACE FUNCTION pad_numbers(text)
              RETURNS text AS
            $BODY$
                SELECT regexp_replace(
                regexp_replace(
                  regexp_replace(
                    regexp_replace(
                      $1, 
                      E'(^|\\D)(\\d{1,3}($|\\D))', E'\\1000\\2', 'g'
                    ), E'(^|\\D)(\\d{4,6}($|\\D))', E'\\1000\\2', 'g'
                  ), E'(^|\\D)(\\d{7}($|\\D))', E'\\100\\2', 'g'
                ), E'(^|\\D)(\\d{8}($|\\D))', E'\\10\\2', 'g'
              );
            $BODY$
              LANGUAGE 'sql' VOLATILE;


select symbol from sample order by pad_numbers(symbol) asc