Conditioning on the iteration number within a loop

[Samyam Shrestha]

Hi,

I want to condition on the iteration number / iteration name within a loop. I'm currently doing it something like below (simplified code):

foreach i in A B C D E {
   ...
   replace x="something" if `i'=="A"
   replace x="something else" if `i'=="B"
​​​​​​​   replace x="something else" if `i'=="C"
​​​​​​​   replace x="something else" if `i'=="D"
​​​​​​​   replace x="something else" if `i'=="E"​​​​​​
   ...
}

But it's showing me errors.

What's the correct way of doing it? Thanks!

[William Lisowski]

replace x="something" if "`i'"=="A"

Without the quotation marks, you are comparing A=="A", and Stata will interpret A as the name of a variable (or an abbreviation for the name of a variable) rather than as the iteration name.

[Daniel Schaefer]

This simplified code isn't really useful. It's clear that this doesn't make sense:

 
  replace x="something" if `i'=="A"

Because if `i'=="A" should say something about whether or any given observation should be replaced or not. It should, therefore, evaluate to true for some observations and false for others. The code you have here doesn't achieve this.

The problem is that it's not clear what you are trying to accomplish, so it's not clear what you should do instead. A data example generated with -dataex- and a clear description of the desired behavior would be very useful here. Also, when you get an error, you should post the exact error. You have 62 posts here, so you're not exactly new to the forum. It's time to learn how to ask a question in a way that is informative enough to get a decent answer.

[Samyam Shrestha]

replace x="something" if "`i'"=="A"

Without the quotation marks, you are comparing A=="A", and Stata will interpret A as the name of a variable (or an abbreviation for the name of a variable) rather than as the iteration name.

Thanks so much. This fixed the problem.