[R] matrix of all difference between rows values

[arun]

Hi,

Though the results from Rui, and me are similar, may be it differs in other instances.

My result: 
dat1<-read.table(text="
 a         10
         b         9
         c         8
         d         7
         e         6
",sep="",header=FALSE,stringsAsFactors=FALSE)
 res1<-apply(toeplitz(dat1[,2]),1,function(x) 10-x)
res1[upper.tri(res1)]<- -1*res1[upper.tri(res1)]
row.names(res1)<-dat1[,1]
 colnames(res1)<-dat1[,1]
 res1 
#  a  b  c  d  e 
#a 0 -1 -2 -3 -4 
#b 1  0 -1 -2 -3 
#c 2  1  0 -1 -2 
#d 3  2  1  0 -1 
#e 4  3  2  1  0 

Rui's solution: 
 t(outer(Table1[,1],Table1[,1],"-")) 
#  a  b  c  d  e 
#a 0 -1 -2 -3 -4 
#b 1  0 -1 -2 -3 
#c 2  1  0 -1 -2 
#d 3  2  1  0 -1 
#e 4  3  2  1  0 


I guess ?expand.grid() might also help you.
dat2<-expand.grid(dat1[,2],dat1[,2])
mat1<-matrix(apply(dat2,1,diff),ncol=5)
dimnames(mat1)<-dimnames(res1)
 mat1
#  a  b  c  d  e
#a 0 -1 -2 -3 -4
#b 1  0 -1 -2 -3
#c 2  1  0 -1 -2
#d 3  2  1  0 -1
#e 4  3  2  1  0


A.K.




----- Original Message -----
From: cleberchaves <cleberchaves at gmail.com>
To: r-help at r-project.org
Cc: 
Sent: Saturday, November 10, 2012 3:55 PM
Subject: Re: [R] matrix of all difference between rows values

Mmmm...

Actually, Rui Barradas is the right!

Arun kirshna, yours script has an error. That repeat the same set of numbers
in all columns...

Anyway, thanks for both!



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