Hi,
I am sure there are better / more efficient ways of doing this, but the
following seems to work ...
ids <- sapply(split(df,df$ID),function(x) {length(x$rel.head)==2 &
any(x$rel.head==1) & any(x$rel.head==3)})
ids <- as.numeric(names(ids)[ids])
added.dummy <- as.numeric(df$ID%in%ids)
cbind(df,added.dummy)
Martyn
-----Original Message-----
From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org]
On Behalf Of gra...@stat.columbia.edu
Sent: 04 October 2011 16:45
To: r-help@r-project.org
Subject: [R] adding a dummy variable...
Hi all,
I have a dataset of individuals where the variable ID corresponds to the
identification of the household where the individual lives. rel.head
stands
for the relationship with the household head. so rel.head=1 is the
household
head, rel.head=2 is the spouse, rel.head=3 is the children.
Here is an example to see how it looks like:
df<-data.frame(ID=c("17100", "17100", "17101", "17102", "17103",
"17103",
"17104", "17104", "17104", "17105", "17105"),
rel.head=c("1","3","1","1","1", "2", "1", "2", "3", "1", "3"))
I want to add a dummy variable that is equal to 1 when these conditions
held simultaneously :
a) the number of rows with same ID is equal to 2
b) the variable rel.head=1 and rel.head=3
So my ideal output is:
ID rel.head added.dummy
1 17100 1 1
2 17100 3 1
3 17101 1 0
4 17102 1 0
5 17103 1 0
6 17103 2 0
7 17104 1 0
8 17104 2 0
9 17104 3 0
10 17105 1 1
11 17105 3 1
Is there a simple way to do that?
Can somebody help?
Thanks in advance,
Grazia
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