Using wrapr::let() with tidyeval

[This article was first published on R – Win-Vector Blog, and kindly contributed to R-bloggers]. (You can report issue about the content on this page here)
Want to share your content on R-bloggers? click here if you have a blog, or here if you don't.

While going over some of the discussion related to my last post I came up with a really neat way to use wrapr::let() and rlang/tidyeval together.

Please read on to see the situation and example.Suppose we want to parameterize over a couple of names, one denoting a variable coming from the current environment and one denoting a column name. Further suppose we are worried the two names may be the same.

We can actually handle this quite neatly, using rlang/tidyeval to denote intent (in this case using “!!” to specify “take from environment instead of the data frame”) and allowing wrapr::let() to perform the substitutions.

suppressPackageStartupMessages(library("dplyr"))
library("wrapr")

mass_col_name = 'mass'
mass_const_name = 'mass'

mass <- 100

let(
  c(MASS_COL = mass_col_name,
    MASS_CONST = mass_const_name),
  
  starwars %>%
    transmute(height,
              (!! MASS_CONST), # `mass` from environment
              MASS_COL,        # `mass` from data.frame
              h100 = height * (!! MASS_CONST),  # env
              hm = height * MASS_COL            # data
    ) %>%
    head()
)

#> # A tibble: 6 x 5
#>   height `(100)`  mass  h100    hm
#>    <int>   <dbl> <dbl> <dbl> <dbl>
#> 1    172     100    77 17200 13244
#> 2    167     100    75 16700 12525
#> 3     96     100    32  9600  3072
#> 4    202     100   136 20200 27472
#> 5    150     100    49 15000  7350
#> 6    178     100   120 17800 21360

All in all, that is pretty neat.

To leave a comment for the author, please follow the link and comment on their blog: R – Win-Vector Blog.

R-bloggers.com offers daily e-mail updates about R news and tutorials about learning R and many other topics. Click here if you're looking to post or find an R/data-science job.
Want to share your content on R-bloggers? click here if you have a blog, or here if you don't.

Never miss an update!
Subscribe to R-bloggers to receive
e-mails with the latest R posts.
(You will not see this message again.)

Click here to close (This popup will not appear again)