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From |
"Nick Cox" <n.j.cox@durham.ac.uk> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
RE: st: combinations of while, if, by, and foreach commands |

Date |
Fri, 19 Sep 2003 00:48:33 +0100 |

Gary Longton > > Metcalfe, Paul wrote: > > > Using Stata 8.1 SE, I'm trying to put together a loop for > what I imagine should be quite a straightforward task. > > > > The relevant part of my data looks like the following: > > > > id cons time > > 5001574 32 > > 5001574 31 > > 5001574 0.278548 30 > > 5001574 0.271683 29 > > 5001574 0.378903 28 > > 5001574 0.291933 27 > > 5001574 0.319807 26 > > 5001574 25 > > 5001574 24 > > 5001574 23 > > 5001574 22 > > 5001574 21 > > 5001574 0.348804 20 > > 5001574 0.247645 19 > > 5001574 0.306516 18 > > 5001574 0.303717 17 > > 5001574 0.310532 16 > > > > I have about 8000 different id values in the full > dataset, observed for different stretches of time with > different numbers of gaps in the cons variable in different > places across the set of ids. > > > > What I would like to do is drop the observations at the > end of the time series where cons=., but keep the > observations in the middle. There are varying numbers of > gaps in the cons time series for different ids, and I want > to keep all of them except the observations at the end of > the time series for each id. I've tried a number of > different combinations of the while, if and foreach > commands, but none of them has worked, so I hoped that > someone on the list could help. > > I think this can be done without looping. -bysort- is your > friend here. > > gen t_neg = -time > bysort id (t_neg) : drop if sum(cons ~= .) == 0 Yes, it's pretty clear I misread the problem! I suppose my excuse is that I didn't imagine that blocks of missings at the beginning could be of use or interest. Nick n.j.cox@durham.ac.uk * * 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: combinations of while, if, by, and foreach commands***From:*Gary Longton <glongton@fhcrc.org>

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