Statistical Analysis: an Introduction using R/R/R as a calculator

R topic: R as a calculator

Text marked like this is used to discuss an R-specific point. The basics of R can be learned by reading these sections in the order they appear in the book. There will also be commands that can be entered directly into R; you should be able to copy-and-paste them directly into your R session. Try the following to see how to use R as a simple calculator

Input:

100+2/3

Result:

> 100+2/3

[1] 100.6667

In the absence of any instructions of what to do with the output of a command, R usually prints the result to the screen. For the time being, ignore the [1] before the answer: we will see that this is useful when R outputs many numbers at once. Note that R respects the standard mathematical rules of carrying out multiplication and division before addition and subtraction: it divides 2 by 3 before adding 100.

R commands can sometimes be rather difficult to follow, so occasionally it can be useful to annotate them with comments. This can be done by typing a hash (#) character: any further text on the same line is ignored by R. This will be used extensively in the R examples in this wikibook, e.g.

Input:

#this is a comment: R will ignore it
(100+2)/3    #You can use round brackets to group operations so that they are carried out first
5*10^2       #The symbol * means multiply, and ^ means "to the power", so this gives 5 times (10 squared), i.e. 500
1/0          #R knows about infinity (and minus infinity)
0/0          #undefined results take the value NaN ("not a number")
(0i-9)^(1/2) #for the mathematically inclined, you can force R to use complex numbers

Result:

> #this is a comment: R will ignore it

> (100+2)/3 #You can use round brackets to group operations so that they are carried out first [1] 34 > 5*10^2 #The symbol * means multiply, and ^ means "to the power", so this is 5 times (10 squared) [1] 500 > 1/0 #R knows about infinity (and minus infinity) [1] Inf > 0/0 #undefined results take the value NaN ("not a number") [1] NaN > (0i-9)^(1/2) #for the mathematically inclined, you can force R to use complex numbers [1] 0+3i

• If you don't know anything about complex numbers, don't worry: they are not important here.
• Note that you can't use curly brackets {} or square brackets [] to group operations together

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