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fix typos in exercise 5.4.3 lines 548 and 559 #590

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fix typos in exercise 5.4.3 lines 548 and 559 #590

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4 changes: 2 additions & 2 deletions transform.Rmd
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Expand Up @@ -545,7 +545,7 @@ select(flights, vars)
```
However there is a problem with the previous code.
The name `vars` could refer to a column named `vars` in `flights` or a different variable named `vars`.
What th code does will depend on whether or not `vars` is a column in `flights`.
What the code does will depend on whether or not `vars` is a column in `flights`.
If `vars` was a column in `flights`, then that code would only select the `vars` column.
For example:
```{r}
Expand All @@ -556,7 +556,7 @@ select(flights, vars)
flights <- select(flights, -vars)
```

However, `vars` is not a column in `flights`, as is the case, then `select` will use the value the value of the , and select those columns.
However, if `vars` is not a column in `flights`, as is the case, then `select` will use the values from the character vector `vars` and select those columns.
If it has the same name or to ensure that it will not conflict with the names of the columns in the data frame, use the `!!!` (bang-bang-bang) operator.
```{r}
select(flights, !!!vars)
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