Convert an r dataframe to correct format to use rep

I have a data frame of the form

A = data.frame(c(1485,1486,1701,1808))
names(A) <- c("ID")

and a second data frame of the form

B = data.frame(1:12)
names(B) <- "value"

I want to be able to use this with rep to form a second column in B such that I have

B$new <- rep(A,each = 3, length.out = 12)

giving

> B
   value  new
1      1 1485
2      2 1485
3      3 1485
4      4 1486
5      5 1486
6      6 1486
7      7 1701
8      8 1701
9      9 1701
10    10 1808
11    11 1808
12    12 1808

this works fine if I define A = c(1485,1486,1701,1808) , but because A is a dataframe it does not. How do I convert A into the correct form to use with rep? I have tried as.list, as.vector, as.integer unsuccessfully.

Solution

As A is a dataframe, you need to specify which column you want to repeat. (here ID)

B$new <- rep(A$ID,each = 3, length.out = 12)
B

#   value  new
#1      1 1485
#2      2 1485
#3      3 1485
#4      4 1486
#5      5 1486
#6      6 1486
#7      7 1701
#8      8 1701
#9      9 1701
#10    10 1808
#11    11 1808
#12    12 1808

In your case, this would also work without using length.out argument

rep(A$ID,each = 3)

It would repeat every ID in A 3 times giving the same result.