What is the difference between the following commands:
abc <- 1:15
abcd <- c(1:15)
abc
abcd
The output is:
> abc <- 1:15
> abcd <- c(1:15)
> abc
[1] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
> abcd
[1] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15