Hi,
You may also try ?reshape()
dat2<- dat1
names(dat2)[-c(1:21)]<- paste(rep(names(dat2)[1:21],8),rep(2:9,each=21),sep="_")
names(dat2)[1:21]<- paste(names(dat2)[1:21],rep(1,21),sep="_")
res1<- reshape(dat2,direction="long",varying=1:ncol(dat2),sep="_")
row.names(res1)<- 1:nrow(res1)
attr(res1,"reshapeLong")<-NULL
###
res<-do.call(rbind,lapply(split(colnames(dat1),((seq_len(ncol(dat1))-1)%/%21)+1),function(x)
{x1<- dat1[,x]; colnames(x1)<- paste0("V",1:21);x1}))##previous solution
changed "paste" to "paste0"
row.names(res)<- 1:nrow(res)
all.equal(res,res2)
#[1] TRUE
A.K.
----- Original Message -----
From: arun <smartpink...@yahoo.com>
To: "w...@dataanalyticscorp.com" <w...@dataanalyticscorp.com>
Cc: R help <r-help@r-project.org>
Sent: Sunday, September 8, 2013 9:29 AM
Subject: Re: [R] melting a data frame
Hi,
You could try:
set.seed(48)
dat1<- as.data.frame(matrix(sample(1:40,189*130,replace=TRUE),ncol=189))
res<-do.call(rbind,lapply(split(colnames(dat1),((seq_len(ncol(dat1))-1)%/%21)+1),function(x)
{x1<- dat1[,x]; colnames(x1)<- paste("V",1:21);x1}))
row.names(res)<- 1:nrow(res)
dim(res)
#[1] 1170 21
A.K.
----- Original Message -----
From: Data Analytics Corp. <w...@dataanalyticscorp.com>
To: R help <r-help@r-project.org>
Cc:
Sent: Saturday, September 7, 2013 11:33 PM
Subject: [R] melting a data frame
Hi,
Suppose I have a data frame with 189 columns. The columns are actually 9
blocks of 21 columns each, each block representing measures on each of 9
products. There are 130 rows. Suppose I extract the first block of 21 columns
and make them into a separate data frame. I then want to take the second block
of 21 columns and rbind it to the first; then the third set of 21 and rbind it
to the first two; etc. The final data frame should have 1170 (= 9 * 130) rows
and 21 columns. Is there an easy way to melt the blocks comparable to using
the melt function in the plyr package (which is why I'm referring to what I
want to do as "melting")? It seems that there should be a simple way to do
this. I used a for loop which worked, but I want to see if there's a more
efficient way.
Thanks,
Walt
________________________
Walter R. Paczkowski, Ph.D.
Data Analytics Corp.
44 Hamilton Lane
Plainsboro, NJ 08536
________________________
(V) 609-936-8999
(F) 609-936-3733
w...@dataanalyticscorp.com
www.dataanalyticscorp.com
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______________________________________________
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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.
