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,







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