I believe matrix indexing makes Arun's complex code wholly unnececessary:
Starting with dat1 as above:
m <- matrix(0,4,4)
m[as.matrix(dat1[,1:2])] <- dat1[,3]
## yielding:
m
[,1] [,2] [,3] [,4]
[1,] 0 2 1 1
[2,] 0 1 2 1
[3,] 0 0 0 2
[4,] 0 0 0 0
If you want to get rid of any nonzero diagonal entries:
diag(m) <- 0 ## does it.
Cheers,
Bert
On Sun, Nov 17, 2013 at 10:27 AM, arun <smartpink...@yahoo.com> wrote:
> Hi,
> May be this helps:
>
> dat1 <- read.table(text="
> data data freq
> 1 2 2
> 1 3 1
> 1 4 1
> 2 3 2
> 2 4 1
> 2 2 1
> 3 4 2",sep="",header=TRUE)
> val<- unique(c(dat1[,1],dat1[,2]))
> dat2 <-expand.grid(data=val,data.1=val)
> library(plyr)
> library(reshape2)
> res <- dcast(join(dat2,dat1),data~data.1,value.var="freq",fill=0)
> row.names(res) <- res[,1]
> res1 <- as.matrix(res[,-1])
> diag(res1) <-0
>
> #or
> m1 <- matrix(0,length(val),length(val),dimnames=list(val,val))
>
> indx1 <- outer(colnames(m1),rownames(m1),paste,sep="")
> indx2 <- paste0(dat1[,1],dat1[,2])
> m1[match(indx2,indx1)] <- dat1[,3]
> diag(m1) <- 0
> m1
> # 1 2 3 4
> #1 0 2 1 1
> #2 0 0 2 1
> #3 0 0 0 2
> #4 0 0 0 0
>
> A.K.
>
>
> Hello ,
> I am working on a project ,
> i need to create an upper triangular matrix from the data in this form;
> data data freq
> 1 2 2
> 1 3 1
> 1 4 1
> 2 3 2
> 2 4 1
> 2 2 1
> 3 4 2
>
> to a triangular matrix in the following form :
> 1 2 3 4
> 1 0 2 1 1
> 2 0 0 2 1
> 3 0 0 0 2
> 4 0 0 0 0
>
> i am new to R please help
>
>
> ______________________________________________
> R-help@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.
--
Bert Gunter
Genentech Nonclinical Biostatistics
(650) 467-7374
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and provide commented, minimal, self-contained, reproducible code.
