Before discussing any of the more complicated stuff, I want to introduce the comment character,
#. It has a simple meaning: it tells R to ignore everything else you’ve written on this line. You won’t have much need of the
# character immediately, but it’s very useful later on when writing scripts (see Chapter 8). However, while you don’t need to use it, I want to be able to include comments in my R extracts. For instance, if you read this:41
seeker <- 3.1415 # create the first variable lover <- 2.7183 # create the second variable keeper <- seeker * lover # now multiply them to create a third one print( keeper ) # print out the value of 'keeper'
##  8.539539
it’s a lot easier to understand what I’m doing than if I just write this:
seeker <- 3.1415 lover <- 2.7183 keeper <- seeker * lover print( keeper )
##  8.539539
You might have already noticed that the code extracts in Chapter 3 included the
# character, but from now on, you’ll start seeing
# characters appearing in the extracts, with some human-readable explanatory remarks next to them. These are still perfectly legitimate commands, since R knows that it should ignore the
# character and everything after it. But hopefully they’ll help make things a little easier to understand.