Implement replace_when()
#7728
Implement replace_when()
#7728
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NEWS.md
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| * `case_when()` is now part of a family of 4 related functions, 3 of which are new: | ||
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| * Use `case_when()` to create a new vector based on logical conditions. | ||
| * Use `replace_when()` to update an existing vector based on logical conditions. | ||
| * Use `recode_values()` to create a new vector by mapping old values to new values. | ||
| * Use `replace_values()` to update an existing vector by mapping old values to new values. | ||
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| We are particularly excited about `recode_values()`, which allows you to easily incorporate a lookup table, and serves as a more holistic replacement for both `case_match()` and `recode()`. | ||
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| This work is a result of [Tidyup 7: Recoding and replacing values in the tidyverse](https://github.com/tidyverse/tidyups/blob/main/007-tidyverse-recoding-and-replacing.md), with a lot of great [feedback](https://github.com/tidyverse/tidyups/pull/29) from the community. |
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Preemptive NEWS bullet for the family of 4, the other 2 are coming up next
| @@ -1,36 +1,83 @@ | |||
| #' A general vectorised if-else | |||
| #' | |||
| #' @description | |||
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I have fully refreshed the case_when() docs, so it's probably worth looking through them holistically
| test_that("replace_when() does not recycle LHS values", { | ||
| # Unlike `case_when()` we get to do this right! | ||
| x <- c(1, 2, 3) | ||
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| expect_snapshot(error = TRUE, { | ||
| replace_when(x, TRUE ~ 0) | ||
| }) | ||
| }) |
| test_that("replace_when() does not allow named `...`", { | ||
| # Purposefully stricter than `case_when()` | ||
| expect_snapshot(error = TRUE, { | ||
| replace_when(1, foo = TRUE ~ 2) | ||
| }) | ||
| }) |
| test_that("replace_when() is a no-op with zero conditions", { | ||
| # Unlike `case_when()`, where when zero conditions are supplied | ||
| # we don't know what kind of vector to build (and we refuse to | ||
| # build an `unspecified` vector, unlike `vec_case_when()`) | ||
| expect_identical(replace_when(1), 1) | ||
| expect_identical(replace_when(1, NULL), 1) | ||
| }) |
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Notable test! replace_when(1) is well defined, while case_when() (that exact call, with no inputs) is not
(Well, case_when() could technically return unspecified(), or incorporate .ptype, .size, and .default if specified, all of which vec_case_when() does, but for the average user it's better to error, and historically that is what case_when() has always done here)
DavisVaughan
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R/case-when.R
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| #' For `case_when()`: | ||
| #' | ||
| #' The RHS inputs will be coerced to their common type. | ||
| #' - The LHS inputs must be logical vectors. |
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For both case_when() and replace_when(), the LHS must be a logical vector. For backward compatibility, case_when() recycles scalar values to their common size, but we no longer recommend this. For replace_when(), the LHS must be the same length as x.
It feels like overall this documentation gets too into the weeds too quickly. We should define the size/type guarantees somewhere, but I feel like it might be better in a details section, rather than in the argument docs.
Part of tidyverse/tidyups#29
Closes #4050 (our second oldest issue!)