Aggeregate funtion calculating the average value of each same index of an array column in a table

Hi,

I have a table with several lines as following;

- Create table mytable (type number , values integer [2]) ;

- Insert into mytable values (1, ‘{ 10, 0 }’ );
- Insert into mytable values (1, ‘{ 20, 30 }’ );
- Insert into mytable values (2, ‘{30, 60}’ );

(In fact, the array size is very big (ex. values [10000]) but the size is
fix. In order to simplify the example, I used an array integer [2]).

I would like to obtain the average value of each index of the array column,
values column.

Is it possible to create an aggregate function which can works as following
? :
(Suppose that avg_mytable is the aggregation function name.)

Ex1) Select avg_mytable (values) from mytable ;

avg_mytable (values)
------------------------
{ 20, 30}

(Explication of the results: 20 because (10+20+30)/3 , 30 because
(0+30+60)/3)

Ex2) Select type, avg_mytable (values) from mytable Group by type ;

Type | avg_mytable (values)
---------------------------------------------
1 | { 15, 15}
2 | { 30, 60}

Thank you so much,

--
View this message in context: http://postgresql.1045698.n5.nabble.com/Aggeregate-funtion-calculating-the-average-value-of-each-same-index-of-an-array-column-in-a-table-tp5732388.html
Sent from the PostgreSQL - general mailing list archive at Nabble.com.