Order vector in R: Letter with number sorts funny

Question

Why can't I sort this vector sort(c("r_1", "r_2", "r_10")) asr_1, r_2, r_10?

The result is:

"r_1"  "r_10" "r_2" 

Answer 1

We can use mixed_sort from gtools. According to ?mixed_sort

These functions sort or order character strings containing embedded numbers so that the numbers are numerically sorted rather than sorted by character value.

library(gtools)
mixedsort(v1)
#[1] "r_1"  "r_2"  "r_10"

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The reason for the sort is that it is not a numeric vector. So, sorting happen

data

v1 <- c("r_1", "r_2", "r_10")