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Reorganize(stack data) a dataframe inducing names

3 messages · Francesca PANCOTTO, Jim Lemon, David Winsemius

Jim Lemon
#
On 07/27/2011 06:28 PM, Francesca wrote:
Hi Francesca,
Oddly enough, I answered a similar question a few days ago. The function 
below turns one or more columns in a data frame into two columns, one a 
factor that defaults to the name(s) of the columns and the other the 
data that was in that column. It also "stretches" the remaining columns 
in the data frame to the same number of rows and sticks the two 
together. It doesn't do exactly what you show above, but it might be 
good enough. A bit of coding could get the factor levels the way you want.

stretch.var<-function(data,to.stretch,
  stretch.names=c("newvar","scores")) {

  datadim<-dim(data)
  to.rep<-which(!(1:datadim[2] %in% to.stretch))
  nrep<-length(to.rep)
  newDF<-data.frame(rep(data[,to.rep[1]],length(to.stretch)))
  if(nrep > 1) {
   for(repvar in 2:nrep)
    newDF[[repvar]]<-rep(data[[to.rep[repvar]]],length(to.stretch))
  }
  newDF<-cbind(newDF,rep(names(data[,to.stretch]),each=datadim[1]),
   unlist(data[,to.stretch]))
  names(newDF)<-c(names(data[to.rep]),stretch.names)
  rownames(newDF)<-NULL
  return(newDF)
}
# read in the data
fp<-read.table("fp.dat",header=TRUE)
# pass only the columns that you want in the result
stretch.var(fp[,c(2,3,6,9)],2:4,c("n1.index","PX_LAST"))

        Date  n1.index PX_LAST
1  04/02/07   PX_LAST    1.34
2  04/09/07   PX_LAST    1.34
3  04/16/07   PX_LAST    1.34
4  04/30/07   PX_LAST    1.36
5  05/07/07   PX_LAST    1.36
6  05/14/07   PX_LAST    1.36
7  05/22/07   PX_LAST    1.36
8  04/02/07 PX_LAST.1    1.36
9  04/09/07 PX_LAST.1    1.36
10 04/16/07 PX_LAST.1    1.36
11 04/30/07 PX_LAST.1    1.40
12 05/07/07 PX_LAST.1    1.40
13 05/14/07 PX_LAST.1    1.40
14 05/22/07 PX_LAST.1    1.40
15 04/02/07 PX_LAST.2    1.33
16 04/09/07 PX_LAST.2    1.33
17 04/16/07 PX_LAST.2    1.33
18 04/30/07 PX_LAST.2    1.37
19 05/07/07 PX_LAST.2    1.37
20 05/14/07 PX_LAST.2    1.37
21 05/22/07 PX_LAST.2    1.37

Jim
David Winsemius
#
On Jul 27, 2011, at 4:28 AM, Francesca wrote:

            

      
      
      
    

        
(only on the last point, since you already have been offered a  
solution ...) You should read more rhelp questions and answers. This  
thread yesterday had three different ways that you could have replaced  
the values of those *.Index columns with their names:

[R] Recoding Multiple Variables in a Data Frame in One Step

Ehlers liked Dunlap's solution, but I thought those two were equally  
clever. Mine was clearly not the best.

            

      
      
      
    

        

      
      
    

        
David Winsemius, MD
West Hartford, CT