### Name: data.frame
### Title: Data Frames
### Aliases: data.frame default.stringsAsFactors
### Keywords: classes methods

### ** Examples

L3 <- LETTERS[1:3]
(d <- data.frame(cbind(x=1, y=1:10), fac=sample(L3, 10, replace=TRUE)))

## The same with automatic column names:
data.frame(cbind(  1,   1:10),     sample(L3, 10, replace=TRUE))

is.data.frame(d)

## do not convert to factor, using I() :
(dd <- cbind(d, char = I(letters[1:10])))
rbind(class=sapply(dd, class), mode=sapply(dd, mode))

stopifnot(1:10 == row.names(d))# {coercion}

(d0  <- d[, FALSE]) # NULL data frame with 10 rows
(d.0 <- d[FALSE, ]) # <0 rows> data frame  (3 cols)
(d00 <- d0[FALSE,])  # NULL data frame with 0 rows