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Re: st: Generating variable that counts number of appearances
From
Nick Cox <[email protected]>
To
[email protected]
Subject
Re: st: Generating variable that counts number of appearances
Date
Sat, 31 Mar 2012 09:55:15 +0100
Use
. ssc desc countmatch
in a loop across friend variables.
Nick
On Sat, Mar 31, 2012 at 6:29 AM, Timothy Malacarne
<[email protected]> wrote:
> Hello,
>
> I'm attempting to create a variable the counts the number of times a unique id value for existing variable 1 appears across all observations variable two. In this case, individuals have unique IDs. They are then asked to name their friends, who appear by their id number in a series of friend variables. Each value is unique in the "ID" variable, but 3 people might nominate the same ID value under the Friend variable. I want to count up how often each individual is named a friend by others.
>
> To do so, I wrote this code:
>
> gen NumberFriends=.;
>
> forval k = 90316050/99798989 {; *the range of ID values
> egen tot`k' = total(Friend1ID==`k');
> replace NumberFriends=tot`k' if `k'==ID;
> drop toad`k';
> };
>
> Unfortunately, it needs to loop over all values in the ID range for it to work and I don't have the computational power to do this in a reasonable amount of time. Is there a computationally more efficient way to count up ID cross references in Stata?
>
> Thanks a lot,
> Tim
>
>
>
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