Re: [R] creating a list of lists from a data frame

From: talepanda <talepanda_at_gmail.com>
Date: Fri, 28 Mar 2008 18:13:27 +0900

try

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

HTH
> 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"
>
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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. Received on Fri 28 Mar 2008 - 09:15:24 GMT

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