Out of sample calculations

[Eilya]

Hello,

I am looking for a solution to expand my matrices in Mata for some out of sample calculations. For example, we have population data for different 5 age-groups in 10 regions over 2000-2020 (matrix is 200x5). I would like to expand the matrix to include 20 additional years for each region (400x5).

Currently, I import the data to Stata and use xtset and tsappend commands and then import the data to Mata. I was hoping that I can do this directly in Mata.

Thank you.

[William Lisowski]

Your question really isn't clear without more detail, or at a minimum it is too difficult to guess at a good answer from what you have shared. Please help us help you. Create and show a small example of your initial matrix - say 2 age groups, 3 regions, 4 years, a 2x12 matrix - and then show what you hope it to be when expanded by 4 additional years into a 2x24 matrix.

The Statalist FAQ provides advice on effectively posing your questions, posting data, and sharing Stata output.

[Eilya]

Sure, here is an example, assuming regions 1 and 2, years 2000 and 2001 and one column of data on population, for example:
mata: I = (1,2000,20\1,2001,22\2,2000,15\2,2001,25)
1 2 3
+----------------------+
1 | 1 2000 20 |
2 | 1 2001 22 |
3 | 2 2000 15 |
4 | 2 2001 25 |
+----------------------+

I want to expand this matrix by adding two more years for each region and have the following:
mata: I = (1,2000,20\1,2001,22\1,2002,.\1,2003,.\2,2000,15\2 ,2001,25\2,2002,.\2,2003,.)


1 2 3
+----------------------+
1 | 1 2000 20 |
2 | 1 2001 22 |
3 | 1 2002 . |
4 | 1 2003 . |
5 | 2 2000 15 |
6 | 2 2001 25 |
7 | 2 2002 . |
8 | 2 2003 . |
+----------------------+

Thank you.

[William Lisowski]

If you install the community-contributed moremata package from SSC, the following seems to do what you want. I added three years to distinguish the number of added years (3) from the number of regions (2) and the number of columns of data (1).

/* one time only highlight and run the following:
ssc install moremata
*/

mata:
I = (1,2000,20\1,2001,22\2,2000,15\2,2001,25)
C1 = mm_expand(range(1,2,1),3,1,1)
C2 = mm_expand(range(2002,2004,1),2,1,0)
C3 = J(2*3,1,.)
J = I \ (C1,C2,C3)
J = sort(J,(1,2))
J
end

: J
           1      2      3
     +----------------------+
   1 |     1   2000     20  |
   2 |     1   2001     22  |
   3 |     1   2002      .  |
   4 |     1   2003      .  |
   5 |     1   2004      .  |
   6 |     2   2000     15  |
   7 |     2   2001     25  |
   8 |     2   2002      .  |
   9 |     2   2003      .  |
  10 |     2   2004      .  |
     +----------------------+

[Eilya]

Perfect. Thanks for this, William. Great to learn about moremata.