How to sort a character vector that contains letters and numbers in R?

[Andrzej]

Hi All,
I would like to sort my df by column that has got following levels or values:

Levels: P_1  P_2  P_3  P_4  P_5  P_6  P_7  P_8  P_9  P_10 P_11

when I use arrange it sorts like this:

that P_10 and P_11 are situated after P_1, but I want it to be after P_9.
How do I do it ? Please help.

[FJCC]

You can reset the levels of the column you want to sort.

library(dplyr)

NUMBERS <- sample(1:11)
DF <- data.frame(Fac = paste("P", NUMBERS, sep = "_"), stringsAsFactors = TRUE)
DF
#>     Fac
#> 1   P_6
#> 2   P_4
#> 3   P_5
#> 4   P_7
#> 5   P_8
#> 6  P_10
#> 7   P_3
#> 8   P_9
#> 9  P_11
#> 10  P_1
#> 11  P_2
arrange(DF, Fac)
#>     Fac
#> 1   P_1
#> 2  P_10
#> 3  P_11
#> 4   P_2
#> 5   P_3
#> 6   P_4
#> 7   P_5
#> 8   P_6
#> 9   P_7
#> 10  P_8
#> 11  P_9
DF <- DF %>% mutate(Fac = factor(Fac, levels = paste("P", 1:11, sep = "_")))
arrange(DF, Fac)
#>     Fac
#> 1   P_1
#> 2   P_2
#> 3   P_3
#> 4   P_4
#> 5   P_5
#> 6   P_6
#> 7   P_7
#> 8   P_8
#> 9   P_9
#> 10 P_10
#> 11 P_11

^{Created on 2022-04-16 by the reprex package (v0.2.1)}

[Andrzej]

Thank you very much indeed, really appreciated.