How to flatten a list of lists?

Question

The tm package extends c so that, if given a set of PlainTextDocuments it automatically creates a Corpus. Unfortunately,

Answer 1

Here's another method that worked for my list of lists.

df <- as.data.frame(do.call(rbind, lapply(foolist, as.data.frame)))

Answer 2

I expect that unlist(foolist) will help you. It has an option recursive which is TRUE by default.

So unlist(foolist, recursive = FALSE) will return the list of the documents, and then you can combine them by:

do.call(c, unlist(foolist, recursive=FALSE))

do.call just applies the function c to the elements of the obtained list

Answer 3

Here's a more general solution for when lists are nested multiple times and the amount of nesting differs between elements of the lists:

 flattenlist <- function(x){  
  morelists <- sapply(x, function(xprime) class(xprime)[1]=="list")
  out <- c(x[!morelists], unlist(x[morelists], recursive=FALSE))
  if(sum(morelists)){ 
    Recall(out)
  }else{
    return(out)
  }
}