Use subinstr and macro when creating new names in a foreach

[Karl Tjensvoll]

Hello, I am doing a lot of -foreach- statements, giving a variable a new name. An example:

 foreach x of varlist $nominal {
capture gen real_`x' = `x'*deflator

Next I want to create an average by year, instead of having avg_real_"name", i would like to have only avg_"name", so I use the real values to do the calculations, but I want to have the nominal names with an avg_ prefix. I tried to do something like this:

foreach x of varlist $real {
capture by year: egen subinstr(`x',$string,"avg",1) = mean(`x')
}

But this gives an error, invalid syntax.

In $string I have "wage asset ...", after I ran the code I figured out that was obviously going to fail. Does anyone have a pointer or a hint to something that would do this? The goal is to create shorter/snipped names without much extra/manual work.

[Nick Cox]

I guess that your loop should be more like

foreach x of global real {
    local X : subinstr local x "real" "", all
    capture by year: egen avg_`X'  = mean(`x')
}

Let's identify the confusions:

1. You can use the subinstr() function on the fly but the form above using equivalent syntax is easier when you're learning.

2. The second argument of subinstr() should in this case be a literal string in "". A single variable name would be legal but otherwise Stata doesn't know what you want.

[Karl Tjensvoll]

That looks exactly what I am looking for, I see that you are doing. I am quite inexperienced with string functions, so this helped alot. I gave it a try and it works like a charm! (One small problem was that "_" is included twice, which is of course solved by removing "_" from old variable or not including it in the new of course )

[Nick Cox]

Indeed. Glad it helped.