Add warning message to joins chapter
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@ -25,6 +25,11 @@ If you're familiar with SQL, you should find the ideas in this chapter familiar,
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### Prerequisites
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### Prerequisites
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::: callout-important
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This chapter relies on features only found in the development version of dplyr.
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If you want to live life on the edge you can get the dev version with `devtools::install_github("tidyverse/dplyr")`.
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:::
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We'll explore the five related datasets from nycflights13 using the join functions from dplyr.
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We'll explore the five related datasets from nycflights13 using the join functions from dplyr.
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```{r}
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```{r}
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@ -329,7 +334,8 @@ airports |>
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```
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```
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**Anti-joins** are the opposite: they return all rows in `x` that don't have a match in `y`.
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**Anti-joins** are the opposite: they return all rows in `x` that don't have a match in `y`.
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They're useful for finding missing values that are **implicit** in the data, the topic of @sec-missing-implicit. Implicitly missing values don't show up as explicit `NA`s but instead only exist as an absence.
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They're useful for finding missing values that are **implicit** in the data, the topic of @sec-missing-implicit.
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Implicitly missing values don't show up as explicit `NA`s but instead only exist as an absence.
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For example, we can find rows that should be in `airports` by looking for flights that don't have a matching destination:
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For example, we can find rows that should be in `airports` by looking for flights that don't have a matching destination:
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```{r}
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```{r}
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