I change the characters in the column wt to the characters "0", "1", "2", "01".
library(dplyr)
set.seed(1)
DF <- data.frame(wt = sample(c("L", "M", "H", "L/M"), 15, replace = TRUE))
DF
#> wt
#> 1 M
#> 2 M
#> 3 H
#> 4 L/M
#> 5 L
#> 6 L/M
#> 7 L/M
#> 8 H
#> 9 H
#> 10 L
#> 11 L
#> 12 L
#> 13 H
#> 14 M
#> 15 L/M
DF <- DF %>% mutate(wt = case_when(wt == "L" ~ "0", wt == "M" ~ "1", wt == "H" ~ "2", wt == "L/M" ~ "01"))
DF
#> wt
#> 1 1
#> 2 1
#> 3 2
#> 4 01
#> 5 0
#> 6 01
#> 7 01
#> 8 2
#> 9 2
#> 10 0
#> 11 0
#> 12 0
#> 13 2
#> 14 1
#> 15 01
Perc <- DF %>% group_by(wt) %>% summarize(Percent = n()/nrow(DF) * 100)
Perc
#> # A tibble: 4 x 2
#> wt Percent
#> <chr> <dbl>
#> 1 0 26.7
#> 2 01 26.7
#> 3 1 20
#> 4 2 26.7
Created on 2019-12-14 by the reprex package (v0.2.1)