How to rename many variables with string suffixes

Question

In Stata, I have a set of variables that all begin with pkg. In their current state, their endings are numeric: pkg1, pkg2, pkg3, pkg4 and so on.

I need to change all of these variables' endings to strings: pkgmz, pkggmz, pkgsp, pkgsptc etc.

I have a column of these string endings, which I can designate as a local list.

For example:

local croplist mz gmz sp sptc mil cof suk tea ric

How do I change the numeric endings to the string endings?

My guess at the code can be found below and the ??? indicate where I am stumped:

local croplist crops mz gmz sp sptc mil cof suk tea ric

foreach x of varlist pkg* {
    local new1 = substr(`x', 1, 3)
    local new2 = ???
    rename `x' ``new1'`new2''
    label var ``new1'`new2'' "Avg district level `new2' price"
}

I wonder if it would be better to utilize the regexr() command, but can't think of a way to include it.

Any help is appreciated.

Answer 1

Here is another way to do it. tokenize puts separate words in macros numbered 1 up. The nested reference ``j'' is handled just in elementary algebra: evaluate the inside macro reference first.

 
tokenize "mz gmz sp sptc mil cof suk tea ric" 
forval j = 1/9 {
    rename pkg`j' pkg``j''
    label var pkg``j'' "Avg district level ``j'' price"
}