cbind and cbind.data.frame

## Hi, I'm having trouble understanding how the cbind function decides what
method to apply to its arguments. Easy cut and paste code below.

## create two columns

c1 <- c("A","A","B","B")

c2 <- 1:4

## cbind outputs a matrix with elements that are characters, seems

reasonable

out <- cbind(c1,c2)

out

    c1  c2

[1,] "A" "1"

[2,] "A" "2"

[3,] "B" "3"

[4,] "B" "4"

class(out)

[1] "matrix"

mode(out)

[1] "character"

## there are two methods associated with cbind. so i assume that

## cbind is calling the data.frame method, because neither of my

## arguments are of ts class

methods(cbind)

[1] cbind.data.frame cbind.ts*


  Non-visible functions are asterisked

## now i explicitly tell cbind to use the data.frame method

## (which is what i assumed it was doing automatically in the last

example)

## but this produces something very different from before, a data.frame

out2 <- cbind.data.frame(c1,c2)

out2

 c1 c2

1  A  1

2  A  2

3  B  3

4  B  4

class(out2)

[1] "data.frame"

mode(out2)

[1] "list"

## can someone explain why these outputs are different. Thanks, James.

c1 <- c("A","A","B","B")

c2 <- 1:4

out <- cbind(c1,c2)

out

class(out)

mode(out)

methods(cbind)

out2 <- cbind.data.frame(c1,c2)

out2

class(out2)

mode(out2)

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