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Update joins.qmd (#1161)

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Jonathan Kitt
2022-11-29 14:46:36 +01:00
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parent e2a4e1a236
commit f0b19065c7
1 changed files with 2 additions and 2 deletions
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joins.qmd
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@@ -724,7 +724,7 @@ x |> left_join(y, by = "key", keep = TRUE)
```{r} ```{r}
#| label: fig-inner-both #| label: fig-inner-both
#| fig-cap: > #| fig-cap: >
#| An left join showing both `x` and `y` keys in the output. #| A left join showing both `x` and `y` keys in the output.
#| fig-alt: > #| fig-alt: >
#| A join diagram showing an inner join betwen x and y. The result #| A join diagram showing an inner join betwen x and y. The result
#| now includes four columns: key.x, val_x, key.y, and val_y. The #| now includes four columns: key.x, val_x, key.y, and val_y. The
@@ -736,7 +736,7 @@ x |> left_join(y, by = "key", keep = TRUE)
knitr::include_graphics("diagrams/join/inner-both.png", dpi = 270) knitr::include_graphics("diagrams/join/inner-both.png", dpi = 270)
``` ```
When we move away from equi-joins we'll always show the keys, because the key values will often different. When we move away from equi-joins we'll always show the keys, because the key values will often be different.
For example, instead of matching only when the `x$key` and `y$key` are equal, we could match whenever the `x$key` is greater than or equal to the `y$key`, leading to @fig-join-gte. For example, instead of matching only when the `x$key` and `y$key` are equal, we could match whenever the `x$key` is greater than or equal to the `y$key`, leading to @fig-join-gte.
dplyr's join functions understand this distinction equi and non-equi joins so will always show both keys when you perform a non-equi join. dplyr's join functions understand this distinction equi and non-equi joins so will always show both keys when you perform a non-equi join.