Something like expand.grid on a list of lists

Question

I have three text documents stored as a list of lists called \"dlist\":

dlist <- structure(list(name = c(\"a\", \"b\", \"c\"), text = list(c(\"the\", \"quick\         


        

Answer 1

Another solution, maybe more generalizable:

do.call(rbind, do.call(mapply, c(dlist, FUN = data.frame, SIMPLIFY = FALSE)))

#     name  text
# a.1    a   the
# a.2    a quick
# a.3    a brown
# b.1    b   fox
# b.2    b jumps
# b.3    b  over
# b.4    b   the
# c.1    c  lazy
# c.2    c   dog

Answer 2

If you convert your dlist to a named list (a better suited structure in my opinion), you can use stack() to get the two column data.frame you want.

(The rev() and setNames() calls in the second line are just one of many ways to adjust the column ordering and names to match the desired output shown in your question.)

x <- setNames(dlist$text, dlist$name)
setNames(rev(stack(x)),  c("name", "text"))
#   name  text
# 1    a   the
# 2    a quick
# 3    a brown
# 4    b   fox
# 5    b jumps
# 6    b  over
# 7    b   the
# 8    c  lazy
# 9    c   dog

Answer 3

Josh's answer is much sweeter but I thought I'd throw my hat in the ring.

dlist <- structure(list(name = c("a", "b", "c"), 
    text = list(c("the", "quick", "brown"), 
    c("fox", "jumps", "over", "the"), c("lazy", "dog"))), 
    .Names = c("name", "text"))

lens <- sapply(unlist(dlist[-1], recursive = FALSE), length)

data.frame(name = rep(dlist[[1]], lens), text = unlist(dlist[-1]), row.names = NULL)

##   name  text
## 1    a   the
## 2    a quick
## 3    a brown
## 4    b   fox
## 5    b jumps
## 6    b  over
## 7    b   the
## 8    c  lazy
## 9    c   dog

That being said the list of lists is a bit of an awkward storage method. A list of vectors (particularly named lists of vectors) would be easier to deal with.