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From |
Derek Darves <darves@uoregon.edu> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: create a variable based on a recurring value in a varlist |

Date |
Thu, 13 Oct 2005 10:32:46 -0700 |

Thanks all for the comments.

I had to rewrite Nick's suggestion (see original message below) to get this to work. In Nick's original formulation every case was rendered a "1". I think the problem is that some of the PID variables were missing for nearly every case. So, I added a little bit of code. I did some error checking and, for the cases that it did mark greater than 1, the data are correct. This does not mean, of course, that I did not miss cases. Since my goal is not find a repeated (non-missing) value in a varlist, will this code do the trick. In other words, does anyone see a way that the code below could have missed a repeated value in varlist? This is the code:

*Start

clear

set mem 1000m

use data, clear

keep pid* index

save safecopy, replace

// Preparations for easy reshape

local i 1

foreach var of varlist pid* {

ren `var' pid`i++'

}

// Solution for Problem

reshape long pid, i(index) j(var)

by index (pid), sort: gen same = sum(pid==pid[_n-1]) if pid!=.

replace same = 0 if same ==.

gen same1=0

bysort index (same) : replace same1 = same[_N]

drop same

reshape wide

save shareddirector, replace

*end

On Oct 13, 2005, at 4:43 AM, Nick Cox wrote:

This is easier done long. save safecopy gen long id = _n reshape long PID, i(id) bysort id (PID) : gen same = PID == PID[_n-1] bysort id (same) : replace same = same[_N] reshape wide Nick n.j.cox@durham.ac.uk Seb Buechteyou could take a "brute force" approach by comparing each var with all

the other vars using two loops:

gen interlock=0

foreach var1 of varlist PID1 PID2 .... {

foreach var2 of varlist PID2 PID3.... {

if "`var1'"!="`var2'" { // making sure you do not compare the

var with itself

replace interlock=1 if `var1' == `var2'

}

}

}

I am not too sure how long it will take to run through these loops.

Derek DarvesI have a group of variables: PID1 - PID15 PID* takes on values from 1 to 8000, and many are missing. Basically, I would like to make a new variable, called interlock, that is equal to 1 if any of the variables in the list are equal to any other variable in the list (not including itself, of course). For example, if PID5==705 and PID14==705 I would like likeinterlock==1Likewise, if none of the the variables in PID* take on the value of any of the other variables in PID*, I would like interlock==0 I tried this: egen interlock = group(pid1_a pid1_b pid2_a pid2_b pid3_a pid3_b pid4_a pid4_b pid5_a pid5_b pid6_a pid6_b pid7_a pid7_b pid8_a pid8_b pid9_a pid9_b pid10_a pid10_b pid11_a pid11_b pid12_a pid12_b pid13_a pid13_b pid14_apid14_b pid15_a), but it returned all missing values when I know that some share a common value in two of the PID* fields. Lastly, not that it should matter, but the above is a simplifying example. In my actual dataset I have about 130 PID*variables. I justmention this in case I am hitting some kind of memory limitation (I am not receiving any errors when I run the command, though, it just doesn't work).* * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

* * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**RE: st: create a variable based on a recurring value in a varlist***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

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