Create a local adding numbers before every elements generated by tokenize

[Chen Samulsion]

Dear Stata users,

I have three variables, I want to create a local that adds sequential number before each variable and interaction of the last two ones. Below is what I want to get:
1 "mpg" 2 "rep78" 3 "foreign" 4 "rep78#foreign"

forvalues n= 1/4 { //In real applying case, the max number of `n' should be determined by count of variables plus 1.
    tokenize mpg rep78 foreign
    local first `1'
    local relabel `relabel' `n' "`first'"
}

display `"`relabel'"' //the result is certainly not what I desire: 1 "mpg" 2 "rep78" 3 "foreign" 4 "rep78#foreign"
1 "mpg" 2 "mpg" 3 "mpg" 4 "mpg"

[Nick Cox]

This may help.

local j = 0
local example mpg rep78 foreign

foreach v of local example {
    local ++j
    local `j' "`v'"
    local wanted `wanted' `j' "``j''"
    if `j' > 1 {
        local J = `j' - 1
        local pair ``J''#``j''
    }
}

mac li

local ++j
local wanted `wanted' `j' "`pair'"

mac li

EDIT This would need more code if it is expected to cope with just one variable name as input. Conversely. the test for j being above 1 isn't needed.

[Chen Samulsion]

Dear Nick Cox, thank you as always. That's great!