Coercion

Finally, we will briefly mention what coercion is in R since it's a topic of confusion for newcomers. When you call a function with an argument of a different type than what was expected, R will try to coerce values so that the function will work, and this can introduce bugs if not handled correctly. R will follow a mechanism similar to what was used when creating vectors.

Strongly typed languages (like Java) will raise exceptions when the object passed to a function is of the wrong type, and will try not to convert the object to a compatible type. However, as we mentioned earlier, R was designed to work out of the box with a lot of unforeseen contexts, so coercion was introduced.

In the following example, we show that if we call our distance() function and pass logical vectors instead of numeric ones, R will coerce the logical vectors into numeric vectors, using TRUE as 1 and FALSE as 0, and proceed with the calculations. To avoid this issue in your own programs, you should coerce data types explicitly with the as.*() functions we mentioned before:

x <- c(1, 2, 3)
y <- c(TRUE, FALSE, TRUE)
distance(x, y)
#> [1] 8