Am Donnerstag, den 16.04.2009, 17:41 +0100 schrieb baptiste auguie:
> Perhaps,
>
> apply(combn(letters[1:4],2), 2, paste,collapse="")
>
> Hope this helps,
Thanks Babtiste,
I use now:
Lines <- "a b c d
13 0 15 16
23 24 25 0
33 34 0 36
0 44 45 46
53 54 0 55"
DF <- read.table(textConnection(Lines), header = TRUE)
cnames <- colnames(DF)
cnames.new <- apply(combn(cnames,2), 2, paste,collapse="")
pairs <- apply(combn(colnames(DF),2), 2, function(x)
DF[,x[1]]*DF[,x[2]] )
colnames(pairs) <- cnames.new
print("pairs="); print(pairs)
cnames.new <- apply(combn(cnames,3), 2, paste,collapse="")
tripels <- apply(combn(colnames(DF),3), 2, function(x)
DF[,x[1]]*DF[,x[2]]*DF[,x[3]])
colnames(tripels) <- cnames.new
print("tripels="); print(tripels)
and I am very satisfied.
Juergen
> baptiste
> On 16 Apr 2009, at 17:33, Juergen Rose wrote:
>
> > Am Donnerstag, den 16.04.2009, 10:59 -0400 schrieb David Winsemius:
> >
> > Thanks David,
> >
> > is there also a shorter way to get the columns names of the new data
> > frames?
> >
> > Juergen
> >
> >> On Apr 16, 2009, at 10:14 AM, Juergen Rose wrote:
> >>
> >>> Hi,
> >>>
> >>> as a R-newcomer I would like to create some new data frames from a
> >>> given
> >>> data frame. The first new data frame should content all pairs of the
> >>> columns of the original data frame. The second new data frame should
> >>> content all tripels of of the columns of the original data frame and
> >>> the
> >>> last the quadrupel of columns. The values in the new data frames
> >>> should
> >>> be the product of two, three our four original single field values.
> >>> For
> >>> pairs and tripels I could realize that task, with the following R
> >>> script:
> >>>
> >>> Lines <- "a b c d
> >>> 13 0 15 16
> >>> 23 24 25 0
> >>> 33 34 0 36
> >>> 0 44 45 46
> >>> 53 54 0 55"
> >>>
> >>> DF <- read.table(textConnection(Lines), header = TRUE)
> >>>
> >>> nrow <-length(rownames(DF))
> >>> cnames <- colnames(DF)
> >>> nc <-length(DF)
> >>>
> >>> nc.pairs <- nc*(nc-1)/2
> >>> # initialize vector
> >>> cnames.new <- c(rep("",nc.pairs))
> >>> ind <- 1
> >>> print(sprintf("nc=%d",nc))
> >>> for (i in 1:(nc-1)) {
> >>> if (i+1 <= nc ) {
> >>> for (j in (i+1):nc) {
> >>> cnames.new[ind] <- paste(cnames[i],cnames[j],sep="")
> >>> ind <- ind+1
> >>> }
> >>> }
> >>> }
> >>>
> >>> ind <- 1
> >>> # initialize data.frame
> >>> pairs <- data.frame(matrix(c(rep(0,nc.pairs*nrow)),ncol=nc.pairs))
> >>> for (i in 1:nc) {
> >>> if (i+1 <= nc ) {
> >>> for (j in (i+1):nc) {
> >>> t <- DF[,i] * DF[,j]
> >>> pairs[[ind]] <- t
> >>> ind <- ind+1
> >>> }
> >>> }
> >>> }
> >>> colnames(pairs) <- cnames.new
> >>> print("pairs="); print(pairs)
> >>
> >> apply(combn(colnames(DF),2), 2, function(x) DF[,x[1]]*DF[,x[2]] )
> >> [,1] [,2] [,3] [,4] [,5] [,6]
> >> [1,] 0 195 208 0 0 240
> >> [2,] 552 575 0 600 0 0
> >> [3,] 1122 0 1188 0 1224 0
> >> [4,] 0 0 0 1980 2024 2070
> >> [5,] 2862 0 2915 0 2970 0
> >>>
> >>>
> >>> nc.tripels <- nc*(nc-1)*(nc-2)/6
> >>> # initialize vector
> >>> cnames.new <- c(rep("",nc.tripels))
> >>> ind <- 1
> >>> print(sprintf("nc=%d",nc))
> >>> for (i in 1:nc) {
> >>> if (i+1 <= nc ) {
> >>> for (j in (i+1):nc) {
> >>> if (j+1 <= nc ) {
> >>> for (k in (j+1):nc) {
> >>> cnames.new[ind] <-
> >>> paste(cnames[i],cnames[j],cnames[k],sep="")
> >>> ind <- ind+1
> >>> }
> >>> }
> >>> }
> >>> }
> >>> }
> >>>
> >>> ind <- 1
> >>> # initialize data.frame
> >>> tripels <-
> >>> data.frame(matrix(c(rep(0,nc.tripels*nrow)),ncol=nc.tripels))
> >>> for (i in 1:(nc-1)) {
> >>> if (i+1 <= nc ) {
> >>> for (j in (i+1):nc) {
> >>> if (j+1 <= nc ) {
> >>> for (k in (j+1):nc) {
> >>> t <- DF[,i] * DF[,j] * DF[,k]
> >>> tripels[[ind]] <- t
> >>> ind <- ind+1
> >>> }
> >>> }
> >>> }
> >>> }
> >>> }
> >>> colnames(tripels) <- cnames.new
> >>> print("tripels="); print(tripels)
> >>
> >>> apply(combn(colnames(DF),3), 2, function(x)
> >> DF[,x[1]]*DF[,x[2]]*DF[,x[3]])
> >> [,1] [,2] [,3] [,4]
> >> [1,] 0 0 3120 0
> >> [2,] 13800 0 0 0
> >> [3,] 0 40392 0 0
> >> [4,] 0 0 0 91080
> >> [5,] 0 157410 0 0
> >>
> >>>
> >>>
> >>> I suppose that here is a much shorter way to get the same results.
> >>> Any
> >>> hint is very much appreciated.
> >>
> >> David Winsemius, MD
> >> Heritage Laboratories
> >> West Hartford, CT
> >>
> >
> > ______________________________________________
> > 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.
>
> _____________________________
>
> Baptiste Auguié
>
> School of Physics
> University of Exeter
> Stocker Road,
> Exeter, Devon,
> EX4 4QL, UK
>
> Phone: +44 1392 264187
>
> http://newton.ex.ac.uk/research/emag
> ______________________________
>
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