The goal of casewhen is to create reusable dplyr::case_when()
functions.
SAS users may recognise a behavior close to the SAS FORMATS.
You can install the development version from GitHub with:
# install.packages("devtools")
devtools::install_github("RLesur/casewhen")During data wrangling with dplyr, one may use several times identical
case_when() clauses in different steps. This can lead to a non-DRY
code.
This package provides a convenient mean to define and reuse
dplyr::case_when() functions.
With casewhen, you can easily create reusable dplyr::case_when()
functions with the function create_case_when():
library(dplyr)
library(casewhen)
people <- tribble(
~name, ~sex, ~seek,
"Mary", "F", "M",
"Henry", "M", "F"
)
cw_sex <- create_case_when(
x == "F" ~ "Woman",
x == "M" ~ "Man",
TRUE ~ as.character(x),
vars = "x"
)
people %>%
mutate(sex_label = cw_sex(sex),
seek_label = cw_sex(seek))
#> # A tibble: 2 x 5
#> name sex seek sex_label seek_label
#> <chr> <chr> <chr> <chr> <chr>
#> 1 Mary F M Woman Man
#> 2 Henry M F Man WomanReusing a case_when() function is mainly convenient when the same
transformation is performed across different datasets.
cw_sexyverse <- create_case_when(
x == "F" | x == "female" & y == "Human" ~ "Woman",
x == "M" | x == "male" & y == "Human" ~ "Man",
TRUE ~ as.character(x),
vars = c("x", "y")
)
people %>%
mutate(sex_label = cw_sexyverse(sex, "Human"))
#> # A tibble: 2 x 4
#> name sex seek sex_label
#> <chr> <chr> <chr> <chr>
#> 1 Mary F M Woman
#> 2 Henry M F Man
starwars %>%
mutate(sex_label = cw_sexyverse(gender, species)) %>%
select(name, gender, species, sex_label) %>%
head()
#> # A tibble: 6 x 4
#> name gender species sex_label
#> <chr> <chr> <chr> <chr>
#> 1 Luke Skywalker male Human Man
#> 2 C-3PO <NA> Droid <NA>
#> 3 R2-D2 <NA> Droid <NA>
#> 4 Darth Vader male Human Man
#> 5 Leia Organa female Human Woman
#> 6 Owen Lars male Human ManYou only have to register the case_when functions to your connection:
con <-
DBI::dbConnect(RSQLite::SQLite(), ":memory:") %>%
add_case_when(cw_sex, cw_sexyverse)
people_db <- copy_to(con, people)
starwars_db <- copy_to(con, starwars %>% select(name, gender, species))
people_db %>%
mutate(sex_label = cw_sex(sex),
seek_label = cw_sex(seek)) %>%
show_query()<SQL>
SELECT `name`, `sex`, `seek`,
CASE
WHEN (`sex` = 'F') THEN ('Woman')
WHEN (`sex` = 'M') THEN ('Man')
WHEN (1) THEN (CAST(`sex` AS TEXT))
END AS `sex_label`,
CASE
WHEN (`seek` = 'F') THEN ('Woman')
WHEN (`seek` = 'M') THEN ('Man')
WHEN (1) THEN (CAST(`seek` AS TEXT))
END AS `seek_label`
FROM `people`people_db %>%
mutate(sex_label = cw_sexyverse(sex, "Human")) %>%
show_query()<SQL>
SELECT `name`, `sex`, `seek`,
CASE
WHEN (`sex` = 'F' OR `sex` = 'female' AND 'Human' = 'Human') THEN ('Woman')
WHEN (`sex` = 'M' OR `sex` = 'male' AND 'Human' = 'Human') THEN ('Man')
WHEN (1) THEN (CAST(`sex` AS TEXT))
END AS `sex_label`
FROM `people`starwars_db %>%
mutate(sex_label = cw_sexyverse(gender, species)) %>%
show_query()<SQL>
SELECT `name`, `gender`, `species`,
CASE
WHEN (`gender` = 'F' OR `gender` = 'female' AND `species` = 'Human') THEN ('Woman')
WHEN (`gender` = 'M' OR `gender` = 'male' AND `species` = 'Human') THEN ('Man')
WHEN (1) THEN (CAST(`gender` AS TEXT))
END AS `sex_label`
FROM `starwars %>% select(name, gender, species)`DBI::dbDisconnect(con)
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