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I have a data frame dd and a vector vec. I want to multiply the dataframe as many times as is the length of the vector. Also, I want to add this vector element as a new column to the dataframe.

# Dummy data dd<- data.frame(id = c(1,2,3,4,5)) vec <- c("a", "b", "d")

Desired output:

 id vec 1 1 a 2 2 a 3 3 a 4 4 a 5 5 a 6 1 b 7 2 b 8 3 b 9 4 b 10 5 b 11 1 d 12 2 d 13 3 d 14 4 d 15 5 d

Originally, I would get the length(vec), use rep(vec, each = length(vec)) and then add this column to rbind(dd, dd,dd). But, if need to replicate dd twenty times, how to do this in a smarter way?

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    You seem to be looking for ?expand.grid Commented Apr 22, 2021 at 15:30

3 Answers 3

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3

We can use crossing

library(tidyr) crossing(dd, vec)
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3

Try:

vec <- data.frame(vec) merge(dd,vec)

Output:

 id vec 1 1 a 2 2 a 3 3 a 4 4 a 5 5 a 6 1 b 7 2 b 8 3 b 9 4 b 10 5 b 11 1 d 12 2 d 13 3 d 14 4 d 15 5 d
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You can try rep like below

transform( dd, vec = rep(vec, each = length(id)) )

which gives

 id vec 1 1 a 2 2 a 3 3 a 4 4 a 5 5 a 6 1 b 7 2 b 8 3 b 9 4 b 10 5 b 11 1 d 12 2 d 13 3 d 14 4 d 15 5 d
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