What's the prefered way to convert a data.frame into a vector?

Following code shows that the results are equal.

```
x <- data.frame(matrix(rnorm(30), nrow = 10))
r1 <- c(x, recursive = TRUE, use.names = FALSE)
r2 <- as.vector(as.matrix(x))
all.equal(r1, r2)
identical(r1, r2)
```

I'd guess `c()`

is the way to go since it's primitive see Chapter 2 or by calling `c`

.