-egen- is very slow...
and I assume you can never do max by hhid, because you might have a
grandmother, mom, and kid, two of whom would have mother's age defined.
How about something like (untested):
. gen int mom_kids=mlineno
. replace mom_kids=lineno if mlineno==.
. sort hhid mom_kids age
. by hhid mom_kids: gen momsage=age[_N]
to start, then worry about grandma next?
-----Original Message-----
From: Friedrich Huebler [mailto:[email protected]]
Sent: Wednesday, September 15, 2004 11:33 AM
To: [email protected]
Subject: st: How to speed up loop
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?
Thank you,
Friedrich Huebler
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