[R] creating dummy variables based on conditions

[arun]

Hi,
You could try this: (if I understand it correctly)
dat1<- read.table(text="
year    id var ans
 2010  1  1  1
 2010  2  0  0
 2010  1  0  1
2010  1  0  1
 2011  2  1  1
 2011  2  0  1
 2011  1  0  0
2011  1  0  0
",sep="",header=TRUE,stringsAsFactors=FALSE)

dat1$newres<-with(dat1,ave(var,id,year,FUN=function(x) any(x==1)*1))
 dat1
#  year id var ans newres
#1 2010  1   1   1      1
#2 2010  2   0   0      0
#3 2010  1   0   1      1
#4 2010  1   0   1      1
#5 2011  2   1   1      1
#6 2011  2   0   1      1
#7 2011  1   0   0      0
#8 2011  1   0   0      0

A.K.

----- Original Message -----
From: Anup Nandialath <anupmenon at gmail.com>
To: r-help at r-project.org
Cc: 
Sent: Sunday, July 14, 2013 7:30 AM
Subject: [R] creating dummy variables based on conditions

Hello everyone,

I have a dataset which includes the first three variables from the demo
data below (year, id and var). I need to create the new variable ans as
follows

If var=1, then for each year (where var=1), i need to create a new dummy
ans which takes the value of 1 for all corresponding id's where an instance
of one was recorded. Sample data with the output is shown below.

    year    id var ans
[1,] 2010  1   1   1
[2,] 2010  2   0   0
[3,] 2010  1   0   1
[4,] 2010  1   0   1
[5,] 2011  2   1   1
[6,] 2011  2   0   1
[7,] 2011  1   0   0
[8,] 2011  1   0   0

Any help on how to achieve this is much appreciated.

Thanks
Anup

    [[alternative HTML version deleted]]

______________________________________________
R-help at r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.