R help - Mar 2010 - Generating variable from 2 others in dataframe

Suppose I have the following dataframe called test:

test<-data.frame(year=rep(1990:2003,5),id=gl(5,length(1990:2003)),eif=as.vector(sapply(1:5,function(z){a<-rep(0,length(1990:2003));a[sample(1:length(1990:2003),sample(1:2,1))]<-1;a})))

year id eif
1990  1   0
1991  1   0
1992  1   0
2000  1   1
1994  1   0
1995  1   0
2001  1   0
1997  1   1
....

I want to create a new variable in this dataframe called "hhtype"
according to the logic:
If eif==1, hhtype = 1
Else if year < 2000, hhtype = 2
Else hhtype = 3

The result would be

year id eif hhtype
1990  1   0 2
1991  1   0 2
1992  1   0 2
2000  1   1 1
1994  1   0 2
1995  1   0 2
2001  1   0 3
1997  1   1 1

I think I can do this with some combination of apply and ifelse, but so far have
not succeeded in putting it all together. Any help would be very much
appreciated!

Thankyou,
Oliver

You have to nest the ifelse's:

test$hhtype <- with(test, ifelse(eif==1,1,ifelse(year<2000,2,3)))

Bert Gunter
Genentech Nonclinical Biostatistics
 
 

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On
Behalf Of o.mannion at auckland.ac.nz
Sent: Monday, March 01, 2010 2:03 PM
To: 'r-help at r-project.org'
Subject: [R] Generating variable from 2 others in dataframe

Suppose I have the following dataframe called test:

test<-data.frame(year=rep(1990:2003,5),id=gl(5,length(1990:2003)),eif=as.vec
tor(sapply(1:5,function(z){a<-rep(0,length(1990:2003));a[sample(1:length(199
0:2003),sample(1:2,1))]<-1;a})))

year id eif
1990  1   0
1991  1   0
1992  1   0
2000  1   1
1994  1   0
1995  1   0
2001  1   0
1997  1   1
....

I want to create a new variable in this dataframe called "hhtype"
according
to the logic:
If eif==1, hhtype = 1
Else if year < 2000, hhtype = 2
Else hhtype = 3

The result would be

year id eif hhtype
1990  1   0 2
1991  1   0 2
1992  1   0 2
2000  1   1 1
1994  1   0 2
1995  1   0 2
2001  1   0 3
1997  1   1 1

I think I can do this with some combination of apply and ifelse, but so far
have not succeeded in putting it all together. Any help would be very much
appreciated!

Thankyou,
Oliver

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