[R] Probably a good use for apply

[jim holtman]

try this:

> test.. <- data.frame(Apples = c(1,3,0,0,1), Pears = c(0,0,1,0,2), Beans =
+ c(1,2,1,0,0))
>
> lapply(seq(nrow(test..)), function(.row){
+     do.call(c, sapply(names(test..), function(.col){
+         rep(.col, test..[[.col]][.row])
+     }))
+ })
[[1]]
  Apples    Beans
"Apples"  "Beans"

[[2]]
 Apples1  Apples2  Apples3   Beans1   Beans2
"Apples" "Apples" "Apples"  "Beans"  "Beans"

[[3]]
  Pears   Beans
"Pears" "Beans"

[[4]]
character(0)

[[5]]
  Apples   Pears1   Pears2
"Apples"  "Pears"  "Pears"



On Wed, May 30, 2012 at 8:50 PM, LCOG1 <jroll at lcog.org> wrote:
> Hi all,
>  I Have a data frame test.. that I would like to convert into a list below
> test_ but am unsure how to efficiently do this.  I can do it in a for loop
> but my data set is huge and it takes forever.  Wondering how I can do this
> more efficiently.  So again how to I go from test.. to test_ below?
> #Data frame
> test.. <- data.frame(Apples = c(1,3,0,0,1), Pears = c(0,0,1,0,2), Beans =
> c(1,2,1,0,0))
>
> #list - my desired outcome
> test_ <- list("1" = c("Apples","Beans"),
>                          "2" = c("Apples","Apples","Apples","Beans","Beans"),
>                          "3" = c("Pears","Beans"),
>                          "4" = c(NULL),
>                          "5" = c("Apples","Pears","Pears"))
>
> Thanks
>
> Josh
>
> --
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>
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-- 
Jim Holtman
Data Munger Guru

What is the problem that you are trying to solve?
Tell me what you want to do, not how you want to do it.