Use recode to clean data frame column

Question

How do I use recode() in order to "clean/strip" certain parts of a column in my data frame? The original data frame looks like this:

df <- data.frame(duration = c("concentration, up to 2 minutes", "concentration, up to 4 minutes", "up to 6 hours"), name = c("Earth", "Water", "Fire"))

The improved version looks this this:

df <- data.frame(duration = c("2 minutes", "4 minutes", "6 hours"), name = c("Earth", "Water", "Fire"))

So, I should delete "concentration," and "up to" or replace it by an empty string using the recode function.

Answer 1

Please find both solutions with dplyr::recode() and with strings::str_remove().

My advice though is to learn the latter too. That way you will be able to learn much more powerful ways of transforming your strings through regular expressions.

Solution with dplyr::recode()

library(dplyr)
#> 
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#> 
#>     filter, lag
#> The following objects are masked from 'package:base':
#> 
#>     intersect, setdiff, setequal, union
df <- data.frame(duration = c("concentration, up to 2 minutes", 
                              "concentration, up to 4 minutes", 
                              "up to 6 hours"), 
                 name = c("Earth", "Water", "Fire"))

df$duration = recode(df$duration, 
                     "concentration, up to 2 minutes" = "2 minutes",
                     "concentration, up to 4 minutes" = "4 minutes",
                     "up to 6 hours" = "6 hours" )
df
#>    duration  name
#> 1 2 minutes Earth
#> 2 4 minutes Water
#> 3   6 hours  Fire

^{Created on 2020-05-04 by the reprex package (v0.3.0)}

Solution with stringr::str_remove()

library(stringr)
df <- data.frame(duration = c("concentration, up to 2 minutes", 
                              "concentration, up to 4 minutes", 
                              "up to 6 hours"), 
                 name = c("Earth", "Water", "Fire"))


df$duration = str_remove( df$duration, "^.*(?=\\d)")
df
#>    duration  name
#> 1 2 minutes Earth
#> 2 4 minutes Water
#> 3   6 hours  Fire

^{Created on 2020-05-04 by the reprex package (v0.3.0)}