creating a list of lists from a data frame

x

lapply(seq(nrow(x)), function(.row){

Dear group,
I have a dataframe (x). (4 rows, 3 columns for
example)

I want to create a master list (my_list) from data
frame.

I want each row of x to be a list.


I tried 3 different ways: writing a loop, using apply,
and going through each row.
Going through each row works for me. since I have 1000
rows, I cannot manually create 1000 lists and combine
them.  I apologize for the long email with all 3
methods I tried. I request you to help me if I can
automate last method. thanks srini

proposal:
x <- data frame

list1 <- list(src=x[1,]$V1,
             title = x[1,]$V2,
             pbset = X[1]$V3)
list2 <- list(src=x[2,]$V1,
             title = x[2,]$V2,
             pbset = X[2]$V3)

master_list <- list(list1,list2)


Solution:
Write a for loop that takes each row and creates a
list.
Append this list to a master list.


Example:

x

   title        src                  probesets
1  chr16q positional CMAR,USP10,PSORS8,WT3,SLI1
2   chr4p positional           ATP5I,MHW1,STGD4
3 chr1q13 positional                    SCARNA2
4  chr4q1 positional                   MORF4LP4

mastr_list = list()

for(i in 1:nrow(x)){

    y=list(src=as.character(x[i,src),
    title=as.character(x[i,]$title),
    probes=as.character(x[i,]$probesets))
     mastr_list[i]=y
   }


problem:
Warning messages:
1: In test[i] = y :
 number of items to replace is not a multiple of
replacement length
2: In test[i] = y :
 number of items to replace is not a multiple of
replacement length
3: In test[i] = y :
 number of items to replace is not a multiple of
replacement length
4: In test[i] = y :
 number of items to replace is not a multiple of
replacement length

mastr_list

[[1]]
[1] "positional"

[[2]]
[1] "positional"

[[3]]
[1] "positional"

[[4]]
[1] "positional"



How can I make my master list.

I tried also apply function and result is not exactly
what I desire.

master_list <- apply(x, 1, list)
master_list

[[1]]
[[1]][[1]]
                      title
src                    probesets
                   "chr16q"
"positional" "CMAR,USP10,PSORS8,WT3,SLI1"


[[2]]
[[2]][[1]]
            title                src
probesets
          "chr4p"       "positional"
"ATP5I,MHW1,STGD4"


[[3]]
[[3]][[1]]
      title          src    probesets
  "chr1q13" "positional"    "SCARNA2"


[[4]]
[[4]][[1]]
      title          src    probesets
   "chr4q1" "positional"   "MORF4LP4"



my final result should look like this:

a =

list(src=as.character(x[1,]$src),title=as.character(x[1,]$title),probes=as.character(x[1,]$probesets))

b =

list(src=as.character(x[2,]$src),title=as.character(x[2,]$title),probes=as.character(x[2,]$probesets))

c =

list(src=as.character(x[3,]$src),title=as.character(x[3,]$title),probes=as.character(x[3,]$probesets))

d =

list(src=as.character(x[4,]$src),title=as.character(x[4,]$title),probes=as.character(x[4,]$probesets))

master_list = list(a,b,c,d)
master_list

[[1]]
[[1]]$src
[1] "positional"

[[1]]$title
[1] "chr16q"

[[1]]$probes
[1] "CMAR,USP10,PSORS8,WT3,SLI1"


[[2]]
[[2]]$src
[1] "positional"

[[2]]$title
[1] "chr4p"

[[2]]$probes
[1] "ATP5I,MHW1,STGD4"


[[3]]
[[3]]$src
[1] "positional"

[[3]]$title
[1] "chr1q13"

[[3]]$probes
[1] "SCARNA2"


[[4]]
[[4]]$src
[1] "positional"

[[4]]$title
[1] "chr4q1"

[[4]]$probes
[1] "MORF4LP4"