...
Further to Martin's reply, if you have missing values in alc_now then
using
gen etoh_now=alc_now=="y"
will not give you what you want because anything that is not "y" will be
coded to zero.
With -encode-, three categories are created: 1 for missing, 2 for "n",
and 3 for "y".
**************
clear*
input str1 alc_now
"y"
"y"
"y"
"y"
" "
"y"
"n"
"y"
"y"
"y"
end
compress
list, noobs
gen etoh_now1=alc_now=="y"
encode alc_now, gen(etoh_now2)
list, noobs nol
recode etoh_now2 1=. 2=0 3=1, gen(etoh_now)
list, noobs nol
**************
______________________________________________
Kieran McCaul MPH PhD
WA Centre for Health & Ageing (M573)
University of Western Australia
Level 6, Ainslie House
48 Murray St
Perth 6000
Phone: (08) 9224-2701
Fax: (08) 9224 8009
email: [email protected]
http://myprofile.cos.com/mccaul
http://www.researcherid.com/rid/B-8751-2008
______________________________________________
If you live to be one hundred, you've got it made.
Very few people die past that age - George Burns
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Michael
McCulloch
Sent: Monday, 28 September 2009 6:25 AM
To: Statalist
Subject: st: efficiently creating 1/0 variables from existing string y/n
variables
Hello,
I have a long list of string variables which contain only "y", "n", or
are missing.
I'm converting them to new numeric variables with values 1 if the old
variable is "y", and 0 if "n".
For example:
gen etoh_now=alc_now=="y"
This gives, correctly:
.. list alc_now etoh_now, clean
alc_now etoh_now
1. y 1
2. y 1
3. y 1
4. y 1
5. y 1
6. y 1
7. n 0
8. y 1
Is there a more efficient way to do this, where I can change "y" to 1
and "n" to 0 without creating a new variable and manually dropping the
old variable?
Michael McCulloch, LAc MPH PhD
Pine Street Foundation
124 Pine Street
San Anselmo, CA 94960-2674
tel: 415-407-1357
fax: 206-338-2391
[email protected]
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