How to invert the order of rows in a matrix

[Filipe Rodrigues]

Dear Statalisters

Apologies in advance for the simplicity of my question. I am sure the is already a forum answering it but I don't seem able to find it.
For the porposes of data presentation I have a square matrix, lets say M=(A,B\C,D), and I want to manipulate it so that M=(C,D\A,D).

clear
matrix define M = (1,2,3\4,5,6\7,8,9)
matrix list M

Would be very grateful if someone could guide on how to do it or to a forum exploring this topic

Many thanks!

[Niels Henrik Bruun]

Dear Filipe
Accidently, you have chosen the wrong forum (for Mata). You'll get better help at the Stata forum.
However, the answer here is (if you mean transposing the matrix):

. matrix define M = (1,2,3\4,5,6\7,8,9)

. matrix list M

M[3,3]
    c1  c2  c3
r1   1   2   3
r2   4   5   6
r3   7   8   9

. matrix trpos = M'

. matrix list trpos

trpos[3,3]
    r1  r2  r3
c1   1   4   7
c2   2   5   8
c3   3   6   9

[Filipe Rodrigues]

Thank you Niels

Your suggestion does something similar to what I was looking for but not exactly what I want. Sorry if my query wasn't clear.
I need to change the order of the rows without changing the order of the columns. For example M = (1,2,3\4,5,6\7,8,9) would be transformed to M = (7,8,9\4,5,6\1,2,3)

Thanks!

PS: I will make sure next time I am more attentive to the forum where I post queries.

[John Mullahy]

Felipe: Here's one solution that uses Mata to do the row reversal

matrix M=(1,2,3)\(4,5,6)\(7,8,9)

matrix list M

mata st_matrix("MR",st_matrix("M")[rows(st_matrix("M"))..1,.])

matrix list MR

[Andrew Musau]

Also, see the following by KitBaum

https://www.stata-journal.com/sjpdf....iclenum=pr0026

[Filipe Rodrigues]

Thank you John Mullahy and Andrew Musau. Both of your suggestion were very helpful and solved my problem.

Many thanks!