Question

How can I convert a data.frame

df <- data.frame(id=c("af1", "af2"), start=c(100, 115), end=c(114,121))

To a list of lists

LoL <- list(list(id="af1", start=100, end=114), list(id="af2", start=115, end=121))

I’ve tried things like

not.LoL <- as.list(as.data.frame(t(df)))

and I’m really not sure what I end up with after this, but it isn’t quite right. My requirement is that I can access, say, the first start by the command

> LoL[[1]]$start
[1] 100

the not.LoL that I currently have gives me the following error:

> not.LoL[[1]]$start
Error in not.LoL[[1]]$start : $ operator is invalid for atomic vectors

Explanations and/or solutions would be greatly appreciated.

Edit: I should have made it clear that “id” here is actually non-unique – there can be multiple elements under a single ID. So I could do with a solution that doesn’t depend on unique IDs to split on.

Answer 1

Using plyr , you can do this

dlply(df,.(id),c)

To avoid grouping by id , if there are multiple ( maybe you need to change column name , id is unique for me)

dlply(df,1,c)