On Oct 12, 2009, at 3:25 PM, David Winsemius wrote:
On Oct 12, 2009, at 2:36 PM, eugen pircalabelu wrote:
Hello R-users,
My toy example:
aa<-c(1:5)
bb<-c(NA,2,NA,4,5)
cc<-c(1,2,NA,4,NA)
dd<-c("A","B","B","A","C")
df<-data.frame(aa,bb,cc,dd=as.factor(dd))
table(unlist(df[,1:3]))
Can anyone point me to what function let's me do a crosstabulation
between table(unlist(df[,1:3])) and df$dd?
I want to find out when dd==A (or B, or C) how many times do the
values 1, 2 ,3,.. appear in df[,1:3]?
Thank you very much!
One way would be to collect the row sums of those columns first, and
then sum by index:
tapply(apply(df[,1:3],1,sum, na.rm=TRUE), df$dd, sum)
A B C
14 9 10
This method is safer than working on table(unlist(df[, 1:3]) since it
does not "break" when an entire row is empty.
> aa<-c(1,2,NA,4,5)
> bb<-c(NA,2,NA,4,5)
> cc<-c(1,2,NA,4,NA)
> dd<-c("A","B","B","A","C")
> df<-data.frame(aa,bb,cc,dd=as.factor(dd))
> table(unlist(df[,1:3]))
1 2 4 5
2 3 3 2 # missing row willno longer be aligned with "dd".
> tapply(table(unlist(df[,1:3])), df$dd, sum)
Error in tapply(table(unlist(df[, 1:3])), df$dd, sum) :
arguments must have same length
> tapply(apply(df[,1:3],1,sum, na.rm=TRUE), df$dd, sum)
A B C
14 6 10
--
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
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David Winsemius, MD
Heritage Laboratories
West Hartford, CT
______________________________________________
R-help@r-project.org mailing list
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
