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```{r, child = "setup.Rmd", include = FALSE}
```
Functions like `starts_with()`, `contains()` or `matches()` are
__selection helpers__ that only work in a selection context.
Examples of valid selection contexts are:
- Inside `dplyr::select()`.
- The `cols` argument of `tidyr::pivot_longer()`.
Using a selection helper anywhere else results in an error:
```{r, error = TRUE}
starts_with("foo")
mtcars[contains("foo")]
subset(mtcars, select = matches("foo"))
```
If you see this error, you've probably used a selection helper in the
wrong place, possibly as the result of a typo (e.g. misplaced comma or
wrong argument name).
|
