The point you raise was discussed in a thread started last week by Ashim
Kapoor. As you say, the -if- command you use
if id = `id'
which should be
if id == `id'
is interpreted as
if id[1] == `id'
This behaviour is documented in various places, among them [P] if and
FAQ . . . . . . . . . . . . . . . . . . . . . if command vs. if
qualifier
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . J.
Wernow
6/00 I have an if command in my program that only seems
to evaluate the first observation, what's going on?
http://www.stata.com/support/faqs/lang/ifqualifier.html
It is not a case of -file- not allowing -if-. There is no way that a
command can prohibit your writing another command before it.
Your syntax is perfectly legal: it just does not do what you want. My
guess is that you want
if id[`i'] == `id' {
By the way, if you only want minimum and maximum from a -summarize-, use
the -meanonly- option [sic].
SJ-7-3 st0135 . . . . . . . . . . . Stata tip 50: Efficient use of
summarize
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N.
J. Cox
Q3/07 SJ 7(3):438--439 (no
commands)
tip on using the meanonly option of summarize to more
quickly determine the mean and other statistics of a
large dataset
Nick
[email protected]
Even Bergseng
I am using the - file write - command to write a series of lines to a
text file. The text file is used as a parameter file for an external
program.
The text file should contain information on several variables for
several different observations and I thus like to loop over observations
and use an - if - condition to write information from the correct
observation in each line. Hovwever, the - file write - command does not
seem to allow - if - conditions. I have tried using the - if - command
with code along these lines:
tempname FILE
file open `FILE' using test.ajo, write replace
sum id
local minid = r(min)
local maxid = r(max)
forvalues i = `minid'(1)`maxid' {
if id=`id' {
file write `FILE' %7.1f (species) _n
}
}
but this only checks the first observation and stops. I can make it work
using - macro - which can take - if -conditions
forvalues i = `minid'(1)`maxid' {
sum species if treid==`l'
local species = r(min)
file write `FILE' %7.1f (`species') _n
}
}
but for several variables for several observations, this seems to be a
bad solution.
Any hints to how I can use - file write - and loop over observations or
use the - if- condition?
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