st: sum the variable based on other variables

[wanhaiyou <wanhaiyou@hnu.edu.cn>]

Hi,Statalist,
I want to creat the sum of one variable based on other variables.For example,
I have the following dataset
v1 v2 v3
1 1 0
0 0 1
1 0 1
1 1 1
0 1 1
0 1 0

If v1=v2, then sum the corresponding value of v1
v1 v2
1 1   equal 
0 0   equal
1 0   not equal
1 1   equal
0 1   not equal
0 1   not equal
if v1=v3, then sum the corresponding value of v1
....

if v3==v1,then sum the corresponding value of v3
if v3=v2,then sum the corresponging value of v3

I have written the following codes

forv i=1/3 {
  forv j=1/3 {
  if `i'~=`j' {
  egen vsum`i'`j'=total(v`i') if v`i'==v`j'
}
}
}

However, I have 5000 variables but the max number of variables is 32,767.
Therefore, this codes cannot be used.

Any suggestions will be appreciated!

--
Bests,

wanhaiyou

Hunan University
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