Rbind does not carry the colnames of a empty data.frame over

Question

How to rbind with empty data.frame? It only carries the column names when there is at least one row but not when it is empty. Empty data.frame is often created before the for loop, so this behavior is annoying.

Example:

test= data.frame(a=1, b=2, c=3)
rbind(test, c(3,4,5))
  a b c
1 1 2 3
2 3 4 5
test= data.frame(matrix(ncol= 3, nrow= 0))
names(test) = c("a", "b", "c")
rbind(test, c(3,4,5))
  X3 X4 X5
1  3  4  5

Answer 1

As Dan Y points out, it's expected behaviour not a bug.

data.table can do this

library(data.table)

# Create empty data.frame
test <- data.frame(matrix(ncol= 3, nrow= 0))
# Give it names
names(test) <- c("a", "b", "c")

# Coerce to data.table
setDT(test)

# rbind vector (set as a list)
x <- rbind(test, as.list(c(3,4,5)), use.names = F, fill = F)

# Coerce back to a data.frame if you wish
setDF(x)

x
>  a b c
 1 3 4 5