apply --> data.frame

It is hard to help when you don't give an example of your input data
and what you want to be computed (in a form one can source or copy
into an R session).  Is the following something like what you are doing?

Suppose you have a function that takes a file name and
returns a list of things of various types extracted from the
file.  A toy example would be
    fileExtract <- function(fileName) {
       fi <-  file.info(fileName)
       byte0 <- if (fi$isdir || fi$size < 1) NA_integer_ else readBin(fileName, what="integer", size=1, n=1)    
       list(Name=basename(fileName), IsDir=fi$isdir, Size=fi$size, FirstByte = byte0, ModTime=fi$mtime)
   } 
Then you can get the list of rows that you want converted to a data.frame
with
   rows <- lapply(dir(R.home(), full.names=TRUE), fileExtract)
E.g., I get
  > dput(rows[1:2])
  list(structure(list(Name = "bin", IsDir = TRUE, Size = 0, FirstByte = NA_integer_, 
      ModTime = structure(1343316337, class = c("POSIXct", "POSIXt"
      ))), .Names = c("Name", "IsDir", "Size", "FirstByte", "ModTime"
  )), structure(list(Name = "CHANGES", IsDir = FALSE, Size = 28204, 
      FirstByte = 87L, ModTime = structure(1340406834, class = c("POSIXct", 
      "POSIXt"))), .Names = c("Name", "IsDir", "Size", "FirstByte", 
  "ModTime")))
Note that the j'th element of each row has a fixed type.
You want a data.frame with columns named "Name", "IsDir",
"Size", and "FirstByte" where the i'th row contains the data in row[[i]].

If that is what you want then here is a function that does a pretty good job of it:
function (listOfRows, nItemsPerRow = unique(vapply(listOfRows, 
    length, 0)), col.names = names(rowTemplate), rowTemplate = listOfRows[[1]], 
    ...) 
{
    stopifnot(length(nItemsPerRow) == 1, nItemsPerRow == length(rowTemplate))
    if (is.null(col.names)) {
        col.names <- sprintf("V%d", seq_len(nItemsPerRow))
    }
    else {
        stopifnot(nItemsPerRow == length(col.names))
    }
    columns <- lapply(structure(seq_len(nItemsPerRow), names = col.names), 
        FUN = function(i) {
            v <- vapply(listOfRows, function(Row) Row[[i]], rowTemplate[[i]])
            if (is.matrix(v)) { # for when length(rowTemplate[[i]])>1 
                v <- t(v)
            }
            v
        })
    data.frame(columns, ...)
}
E.g.,

apply --> data.frame

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