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From |
Ulrich Kohler <kohler@wz-berlin.de> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
st: Re: How to speed up loop |

Date |
Wed, 15 Sep 2004 18:47:37 +0200 |

Nick's approach is much better than mine. But probably with an if qualifier: . by hhid : gen mage = age[mlineno] if mlineno < . uli Nick Cox wrote: > Looks like > > by hhid : gen mage = age[mlineno] > > to me. No loops, no -merge-. > > Nick > n.j.cox@durham.ac.uk > > Friedrich Huebler > > > I appreciate the responses that I received so far but realize that my > > initial message was not precise enough. > > > > The variable mlineno lists the line number of a household member's > > mother. In household 1 in my example data, household member 2 is the > > mother of household member 3. In household 2, 1 is the mother of 2, > > and 3 is the mother of 4 and 5. I would like to create a variable > > that lists the age of each household member's mother. The result > > should look like this: > > > > hhid lineno age mlineno mage > > 1 1 32 . . > > 1 2 30 . . > > 1 3 5 2 30 > > 2 1 68 . . > > 2 2 41 1 68 > > 2 3 40 . . > > 2 4 17 3 40 > > 2 5 14 3 40 > > > > The loop that I am using to create the variable mage works perfectly > > but it is very slow with a large number of observations. > > > > Friedrich > > > > --- Friedrich Huebler <huebler@rocketmail.com> wrote: > > > I am looking for advice to speed up a loop. The loop determines > > > characteristics of other household members in household survey data > > > and is taken from this Stata FAQ: > > > > > > http://www.stata.com/support/faqs/data/members.html > > > > > > The data has the variables hhid (household ID), lineno (line number > > > of household member), age, and mlineno (mother's line number). > > > > > > hhid lineno age mlineno > > > 1 1 32 . > > > 1 2 30 . > > > 1 3 5 2 > > > 2 1 68 . > > > 2 2 41 1 > > > 2 3 40 . > > > 2 4 17 3 > > > 2 5 14 3 > > > > > > The following code creates the variable mage with the mother's age. > > > > > > gen byte mage=. > > > sum lineno, meanonly > > > forvalues i = 1/`r(max)' { > > > gen byte tag = 1 if lineno==`i' > > > bysort hhid: egen byte iage = max(tag*age) > > > replace mage=iage if mlineno==`i' > > > drop tag iage > > > } > > > > > > I tried changing -bysort hhid- to -by hhid- but the time needed for > > > the loop is the same. Running the loop -quietly- also makes no > > > difference. Can anything be done to make this loop go faster? > > * > * 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/ -- kohler@wz-berlin.de +49 (030) 25491-361 * * 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**:**st: RE: Re: How to speed up loop***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

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