How to manipulate filenames with a macro

Question

I want to save the results of my Stata forvalues loop into individual files. One component of the filename should be the value j assigned to the macro within a forvalues loop.

Apparently my code leads to an instruction always to save with 1995. As such, I get messages telling me that this file already exists.

I am using the following code:

local j = 1995

forvalues `j'= 1995 / 2012 {  
    clear  
    use "/Users/carl/Desktop/STATA/Neustart/eventdates.dta", clear  
    keep if eventyear == `j'  
    sort acq_cusip eventdate  
    compress  
    save "/Users/carl/Desktop/STATA/Neustart/eventdates_`j'.dta"  
}

Does anyone have an answer to that?

Answer 1

In your original code Stata sees `j' inside the forvalues command (instead of the correct j), so it starts to evaluate that before it starts the loop. So what is eventually run is

forvalues 1995=1995/2012 {

This means that forvalues is changing the content of the local macro confusingly but legally called `1995' to 1995 in the first iteration, 1996 in the second iteration, etc. So when you refer to the local `j' inside the loop, it will not have changed and remains at the original value which you defined before the loop.

The way to solve this is to replace:

local j = 1995
forvalues `j' = 1995/2012 {

with:

forvalues j = 1995/2012 {