repeating a sequence of values in a matrix

[Ariel Linden]

Hi All,

I am trying to generate a sequence of 1's in row of a matrix where all other values remain 0. More specifically in the example code below, for the first row, the first 4 columns should be coded 1, in the second row, columns 5 through 8 should be coded 1, in row 3, columns 9 through 12 should be coded 1, etc...

I am trying to elaborate on the basic matrix code BB[1,1..4] = 1, to no success...

All help is welcome!

Ariel

local margcnt = 4

mat BB = J(`margcnt',`margcnt'^2,0)
                
forval i = 1/`margcnt' {
    mat FF = BB[`i', ((`i' - 1) * `margcnt' + 1)..(`i' * `margcnt')] = 1
}

[Andrew Musau]

local margcnt = 4
clear matrix
mat B= I(`margcnt')
forval i=1/`margcnt'{
    forval j=1/`margcnt'{
        mat BB=nullmat(BB), B[`i', 1...]'
    }
}
mat l BB

Res.:

. mat l BB

BB[4,16]
    r1  r1  r1  r1  r2  r2  r2  r2  r3  r3  r3  r3  r4  r4  r4  r4
c1   1   1   1   1   0   0   0   0   0   0   0   0   0   0   0   0
c2   0   0   0   0   1   1   1   1   0   0   0   0   0   0   0   0
c3   0   0   0   0   0   0   0   0   1   1   1   1   0   0   0   0
c4   0   0   0   0   0   0   0   0   0   0   0   0   1   1   1   1

[Ariel Linden]

Thank you, Andrew! That is exactly what I was looking for!

Ariel