Using cbind on an arbitrarily long list of objects

The do.call function is very useful here:

A <- 1:10B <- 11:20C <- 20:11> do.call(cbind, list(A,B,C))      [,1] [,2] [,3] [1,]    1   11   20 [2,]    2   12   19 [3,]    3   13   18 [4,]    4   14   17 [5,]    5   15   16 [6,]    6   16   15 [7,]    7   17   14 [8,]    8   18   13 [9,]    9   19   12[10,]   10   20   11

First you need to get the objects you want and store them together as a list; if you can construct their names as strings, you use the get function. Here I create two variables, A and B:

> A <- 1:4> B <- rep(LETTERS[1:2],2)

I then construct a character vector containing their names (stored as ns) and get these variables using lapply. I then set the names of the list to be the same as their original names.

> (ns <- LETTERS[1:2])[1] "A" "B"> obj.list <- lapply(ns, get)> names(obj.list) <- ns> obj.list$A[1] 1 2 3 4$B[1] "A" "B" "A" "B"

Then you can use do.call; the first argument is the function you want and the second is a list with the arguments you want to pass to it.

> do.call(cbind, obj.list)     A   B  [1,] "1" "A"[2,] "2" "B"[3,] "3" "A"[4,] "4" "B"

However, as aL3xa correctly notes, this makes a matrix, not a data frame, which may not be what you want if the variables are different classes; here my A has been coerced to a character vector instead of a numeric vector. To make a data frame from a list, you just call data.frame on it; then the classes of the variables are retained.

> (AB <- data.frame(obj.list))  A B1 1 A2 2 B3 3 A4 4 B> sapply(AB, class)        A         B "integer"  "factor" > str(AB)'data.frame':   4 obs. of  2 variables: $ A: int  1 2 3 4 $ B: Factor w/ 2 levels "A","B": 1 2 1 2

You should bare in mind, though, that cbind will return an atomic vector (matrix) when applied solely on atomic vectors (double in this case). As you can see in @prasad's and @Aaron's answers, resulting object is a matrix. If you specify other atomic vectors (integer, double, logical, complex) along with character vector, they will get coerced to character. And then you have a problem - you have to convert them to desired classes. So,

if A, B, C & D are all vectors of equal length, one can create data.frame ABCD with

ABCD <- data.frame(A, B, C, D)

Perhaps you should ask "how can I easily gather various vectors of equal length and put them in a data.frame"? cbind is great, but sometimes it's not what you're looking for...