Learning R

Chapter 2. A Scientific Calculator

R is at heart a supercharged scientific calculator, so it has a fairly comprehensive set of mathematical capabilities built in. This chapter will take you through the arithmetic operators, common mathematical functions, and relational operators, and show you how to assign a value to a variable.

Chapter Goals

After reading this chapter, you should:

• Be able to use R as a scientific calculator
• Be able to assign a variable and view its value
• Be able to use infinite and missing values
• Understand what logical vectors are and how to manipulate them

Mathematical Operations and Vectors

The + operator performs addition, but it has a special trick: as well as adding two numbers together, you can use it to add two vectors. A vector is an ordered set of values. Vectors are tremendously important in statistics, since you will usually want to analyze a whole dataset rather than just one piece of data.

The colon operator, :, which you have seen already, creates a sequence from one number to the next, and the c function concatenates values, in this case to create vectors (concatenate is a Latin word meaning “connect together in a chain”).

Variable names are case sensitive in R, so we need to be a bit careful in this next example. The C function does something completely different to c:^[6]

1:5 + 6:10         #look, no loops!

## [1]  7  9 11 13 15

c(1, 3, 6, 10, 15) + c(0, 1, 3, 6, 10)

## [1]  1  4  9 16 25

Tip

The colon operator and the c function are used almost everywhere in R code, ...