Trim factor labels for multiple variables at the same time

user_5921180 0
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This is my toy dataset: 

 library(tidyverse)
dat <- tibble (x1 = c("False - very long label specific to x1", "False - very long label specific to x1", "True - very long label specific to x1", "True - very long label specific to x1"),
               x2 = c("False - very long label specific to x2", "False - very long label specific to x2", "False - very long label specific to x2", "True - very long label specific to x2"),
               y = c(10, 5, 12, 4)) %>% mutate_at(vars(x1:x2), factor)
head(dat)
#> # A tibble: 4 x 3
#>   x1                                x2                                    y
#>   <fct>                             <fct>                             <dbl>
#> 1 False - very long label specific~ False - very long label specific~    10
#> 2 False - very long label specific~ False - very long label specific~     5
#> 3 True - very long label specific ~ False - very long label specific~    12
#> 4 True - very long label specific ~ True - very long label specific ~     4

I would like to trim the very long factor labels, they all have two things in common:

  1. all start with True or False
  2. include the column name (ie the factor labels for each column are unique)

I would like to simplify this, and have only something like True and False for each factor column. This is my desired output: 


#> # A tibble: 4 x 3
#>   x1    x2        y
#>   <fct> <fct> <dbl>
#> 1 False False    10
#> 2 False False     5
#> 3 True  False    12
#> 4 True  True      4

I think it should work with something like mutate_at and fct_relabel and maybe str_trunc, but I could not figure it out.

forcats dplyr r
1 Answers

We can use trimws with whitespace

library(dplyr)
dat %>% 
    mutate_if(is.factor, ~ factor(trimws(., whitespace = "\\s*-.*")))
# A tibble: 4 x 3
#  x1    x2        y
#  <fct> <fct> <dbl>
#1 False False    10
#2 False False     5
#3 True  False    12
#4 True  True      4

Or with fct_relabel and str_remove

library(forcats)
library(stringr)
dat %>% 
    mutate_if(is.factor, ~ fct_relabel(., ~str_remove(., '\\s*-.*')))

Or using data.table

library(data.table)
m1 <- names(which(sapply(dat, is.factor)))
setDT(dat)[, (nm1) := lapply(.SD, function(x) 
        factor(sub('\\s*-.*', "", x))) , .SDcols = nm1]
user_37322710
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