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transposing a list of vectors

6 messages · Michael Friendly, jim holtman, Henrique Dallazuanna +1 more

Michael Friendly
# 
I have a list of vectors, all forced to be the same length:

testlist <- list(
    shape=c(0, 0, 2),
  cell.fill=c("red","blue","green"),
    back.fill=rep("white",3),
    scale.max=rep(100,3)
    )
 > str(testlist)
List of 4
 $ shape    : num [1:3] 0 0 2
 $ cell.fill: chr [1:3] "red" "blue" "green"
 $ back.fill: chr [1:3] "white" "white" "white"
 $ scale.max: num [1:3] 100 100 100
 >

I need to 'transpose' them into a list of lists with named values like so:

wanted <- list(
    list(shape=0, cell.fill="red", back.fill="white", scale.max=100),
    list(shape=0, cell.fill="blue", back.fill="white", scale.max=100),
    list(shape=2, cell.fill="green", back.fill="white", scale.max=100)
    )
 > str(wanted)
List of 3
 $ :List of 4
  ..$ shape    : num 0
  ..$ cell.fill: chr "red"
  ..$ back.fill: chr "white"
  ..$ scale.max: num 3
 $ :List of 4
  ..$ shape    : num 0
  ..$ cell.fill: chr "blue"
  ..$ back.fill: chr "white"
  ..$ scale.max: num 3
 $ :List of 4
  ..$ shape    : num 2
  ..$ cell.fill: chr "green"
  ..$ back.fill: chr "white"
  ..$ scale.max: num 3
 >

How can I do this in general?
Henrique Dallazuanna
# 
Try this:

#'1) But apply converts all to 'character'
apply(as.data.frame(testlist), 1, as.list)

#2)
lapply(split(x <- as.data.frame(testlist), 1:nrow(x)), as.list)
On Fri, Jan 15, 2010 at 11:09 AM, Michael Friendly <friendly at yorku.ca> wrote:

  
    

      
      
    

  


  


      

    

    

      
      

        


  

        

      Gabor Grothendieck
    

    

      
      #
    

  


  

      
This gives the result you asked for:

DF <- as.data.frame(testlist)
lapply(split(DF, 1:nrow(DF)), unclass)

although it might be good enough to just do this depending on what you need:

DF <- as.data.frame(testlist)
split(DF, 1:nrow(DF)

        
On Fri, Jan 15, 2010 at 8:09 AM, Michael Friendly <friendly at yorku.ca> wrote:

            

      
      
      
    

        

      
      
    

  
  


  


      

    

    

      
      

        


  

        

      Michael Friendly
    

    

      
      #
    

  


  

      
Thanks, Henrique
I *do* need to preserve the type of each list element (num or chr).
Thus, a first step might be

 > as.data.frame(testlist, stringsAsFactors=FALSE)
  shape cell.fill back.fill scale.max
1     0       red     white       100
2     0      blue     white       100
3     2     green     white       100
 > str(as.data.frame(testlist, stringsAsFactors=FALSE))
'data.frame':   3 obs. of  4 variables:
 $ shape    : num  0 0 2
 $ cell.fill: chr  "red" "blue" "green"
 $ back.fill: chr  "white" "white" "white"
 $ scale.max: num  100 100 100

I think, with this mod, your #2 gives me what I want:

 wanted.henrique <- lapply(split(x <- as.data.frame(testlist, 
stringsAsFactors=FALSE), 1:nrow(x)), as.list)
 > str(wanted.henrique)
List of 3
 $ 1:List of 4
  ..$ shape    : num 0
  ..$ cell.fill: chr "red"
  ..$ back.fill: chr "white"
  ..$ scale.max: num 100
 $ 2:List of 4
  ..$ shape    : num 0
  ..$ cell.fill: chr "blue"
  ..$ back.fill: chr "white"
  ..$ scale.max: num 100
 $ 3:List of 4
  ..$ shape    : num 2
  ..$ cell.fill: chr "green"
  ..$ back.fill: chr "white"
  ..$ scale.max: num 100

        
Henrique Dallazuanna wrote: