$a
[1] 1
$b
[1] 4
In the first example, we are mixing integer and character modes, a
combination that R chooses to reduce to the latter mode. In the second
example, R considers the list mode to be of lower precedence in mixed
expressions. We’ll discuss this further in Section 4.3.
You probably will not wish to write code that makes such combinations,
but you may encounter code in which this occurs, so it’s important to under-
stand the effect.
Another point to keep in mind is thatc()has a flattening effect for vec-
tors, as in this example:
c(5,2,c(1.5,6))
[1] 5.0 2.0 1.5 6.0
Those familiar with other languages, such as Python, may have expected
the preceding code to produce a two-level object. That doesn’t occur with R
vectors though you can have two-level lists, as you’ll see in Chapter 4.
In the next chapter, we move on to a very important special case of vec-
tors, that of matrices and arrays.
Vectors 57