[R] Insert null columns and rows into a matrix to make it square

[arun]

HI,
You could try this:

dat1<- read.table(text="
A  B  C  D
A 1  2  3  4
E 5  6  7  8
F 9 10 11 12
",sep="",header=TRUE,stringsAsFactors=FALSE)


dat1$ID<-row.names(dat1)
library(reshape2)
dat1New<-melt(dat1,id.var="ID")
dat2<- data.frame(expand.grid(ID=LETTERS[1:6],variable=LETTERS[1:6]),value=0)
datM<-merge(dat1New,dat2,all=TRUE)


 res<-xtabs(value~ID+variable,data=datM)

 names(attr(res,"dimnames"))<-NULL
 res
#   A  B  C  D  E  F
#A  1  2  3  4  0  0
#B  0  0  0  0  0  0
#C  0  0  0  0  0  0
#D  0  0  0  0  0  0
#E  5  6  7  8  0  0
#F  9 10 11 12  0  0

#or
res2<-dcast(datM,ID~variable,value.var="value",sum)
row.names(res2)<- res2[,1]
res2New<- res2[,-1]
 res2New
#  A  B  C  D E F
#A 1  2  3  4 0 0
#B 0  0  0  0 0 0
#C 0  0  0  0 0 0
#D 0  0  0  0 0 0
#E 5  6  7  8 0 0
#F 9 10 11 12 0 0



#or

dat2<- expand.grid(ID=LETTERS[1:6],variable=LETTERS[1:6])
datM<-merge(dat1New,dat2,all=TRUE)
 dcast(datM,ID~variable,value.var="value",fill=0)
#  ID A  B  C  D E F
#1  A 1  2  3  4 0 0
#2  B 0  0  0  0 0 0
#3  C 0  0  0  0 0 0
#4  D 0  0  0  0 0 0
#5  E 5  6  7  8 0 0
#6  F 9 10 11 12 0 0

A.K.


Hi, 
I wish to convert rectangular matrices such as this: 
  A  B  C  D 
A 1  2  3  4 
E 5  6  7  8 
F 9 10 11 12 
into square ones with null rows and columns named with the missing names such as this: 
  A  B  C  D  E  F 
A 1  2  3  4  0  0 
B 0  0  0  0  0  0 
C 0  0  0  0  0  0 
D 0  0  0  0  0  0 
E 5  6  7  8  0  0 
F 9 10 11 12  0  0 
Could anyone give me a hand please. 
Thanks 
Mariki