R: losing column names when adding rows to an empty data frame

Question

I am just starting with R and encountered a strange behaviour: when inserting the first row in an empty data frame, the original column names get lost.

example:

Answer 1

FWIW, an alternative design might have your functions building vectors for the two columns, instead of rbinding to a data frame:

ones <- c()
twos <- c()

Modify the vectors in your functions:

ones <- append(ones, 5)
twos <- append(twos, 6)

Repeat as needed, then create your data.frame in one go:

a <- data.frame(one=ones, two=twos)