I'm trying to create separate .csv files for each group in a data frame grouped with dplyr's group\_by function. So far I have something like

```
by_cyl <- group_by(mtcars, cyl)
do(by_cyl, write_csv(., "test.csv"))

```

As expected, this writes a single .csv file with only the data from the last group. How can I modify this to write multiple .csv files, each with filenames that include cyl?