rbind.data.frame converts character column to factor (PR#9917)

Full_Name: S?bastien Villemot
Version: 2.5.1
OS: Debian GNU/Linux (Testing aka "Lenny")
Submission from: (NULL) (193.51.127.120)


Here is the transcript of a R session under version 2.5.1:

x <- data.frame(a = I(character(0)))
typeof(x$a)

[1] "character"

x <- rbind(x, list(a = "foo"))
typeof(x$a)

[1] "integer"

The column "a" has been converted from character to factor.

This was not happening under version 2.4.0 Patched (2006-11-25 r39997):

x <- data.frame(a = I(character(0)))
typeof(x$a)

[1] "character"

x <- rbind(x, list(a = "foo"))
typeof(x$a)

[1] "character"

Furthermore, the bug doesn't show up (in 2.5.1) if the data frame is initially
non-empty:

x <- data.frame(a = I("bar"))
typeof(x$a)

[1] "character"

x <- rbind(x, list(a = "foo"))
typeof(x$a)

[1] "character"

Best,

S?bastien Villemot