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From | <Seyi.Soremekun@lshtm.ac.uk> |
To | <statalist@hsphsun2.harvard.edu> |
Subject | Re: st: copying a string variable to all rows within a group |
Date | Wed, 29 Feb 2012 11:31:03 +0000 |
Thanks Nick. I was using search terms (phrases including egen, copy, string, row, etc) that didn't bring up that particular FAQ. These two do as I expected, however they don't do exactly the same thing (discrepancy of 2-3 in total number of changes made): 1. bysort groupvar (oldvar) : replace oldvar = oldvar[_N] 2. bysort groupvar : replace oldvar = oldvar[_n-1] if missing(oldvar) & _n > 1 This one on the other hand appears to do something completely different - including returning many of the original (single) observations to missing: 3. bysort groupvar : replace oldvar = oldvar[1] I've used the first option as this results in the largest number of changes (3 more than second option), and intuitively seems more accurate - maybe not the most robust of reasons but no other more sensible ones come to mind I'm afraid. thanks, Seyi >>> Nick Cox <njcoxstata@gmail.com> 2/29/2012 9:01 AM >>> For "row" read "observation". We know what you mean, but that is the correct Stata terminology. bysort groupvar (oldvar) : replace oldvar = oldvar[_N] Alternatively, bysort groupvar : replace oldvar = oldvar[1] will probably work too. Alternatively, bysort groupvar : replace oldvar = oldvar[_n-1] if missing(oldvar) & _n > 1 will probably work too. This last is an FAQ FAQ . . . . . . . . . . . . . . . . . . . . . . . Replacing missing values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. J. Cox 2/03 How can I replace missing values with previous or following nonmissing values? http://www.stata.com/support/faqs/data/missing.html On Wed, Feb 29, 2012 at 8:28 AM, <Seyi.Soremekun@lshtm.ac.uk> wrote: , > If I have a numeric variable "oldvar" which appears on only the first row of a set of rows defined by a group variable "groupvar" (rest of oldvar rows are blank), it is easy enough to copy oldvar down all rows within groupvar: > > bysort groupvar: egen newvar=max(oldvar) // can equally use =min(oldvar) as there is only 1 value of oldvar. > > How might I do the same to copy a string oldvar to all rows - again it only appears once within the group, but not necessarily on the first row. > * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/