How to sort a vector by alternating its values

user_13321647 0
Viewed 45

How can I order this vector:

x <- c(4,4,5,5)
[1] 4 4 5 5

to

x <- c(4,5,4,5)
[1] 4 5 4 5

I am not sure. I have tried TRUE, FALSE.

vector r sorting
2 Answers

We may use rowid

library(data.table)
x[order(rowid(x))]
[1] 4 5 4 5
user_37322710

With base R we can use ave

> x[order(ave(x, x, FUN = seq_along))]
[1] 4 5 4 5
user_121587570
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