# R Tutorial

Introduction to R | __Tutorial Main Menu__ | Developing Scatterplots

# Section 2: Using R for basic calculations

R has a fairly comprehensive set of mathematical functions and relational operators. This section will show you how to assign a value to a variable as well as how to use R like a scientific calculator.

## Mathematical Operations and Vectors

**NOTE**: Variable names are case sensitive in R, so it is very important to understand that X is not the same as x and Y isn't the same as y.

**Figure 2-1**

**Figure 2-2**

Here are a few examples of calculations(with their returned results) that can be performed in R:

> **10 + 12**

[22]

> **1 + 5 -2/1**

[4]

> **sum(1,2,3,4,5)**

[15]

> **median(1:5)**

[3]

This is an example of how creating a C function can perform simple subtraction:

> **c(2,3,5,7,11,13) - 2**

[0 1 3 5 9 11]

## Mathmatical Functions

**Figure 2-3**

**Trigonometry**(sin,cos and tan) as well as their inverses(asin, acos and atan)

**Logarithmic/Exponents**(log and exp) and their varients(log1p and expm1)

## Assigning Variables

Assigning a variable in R is done by using either **<-** or **=**. For example, if we wanted to assign values to x and y, it would appear in R like this:

**x <- 5**

**y = 10**

Once these variables are assigned you can use the variables in further calculation:

> **x + 2 + y -3**

[14]

## Special Numbers

R has four special numeric values to help with arithmetic:

Inf Infinity

-Inf Negative Infinity

NaN Stands for "Not a Number"

NA Placeholder for Missing Values

## Classes

All variables in R have a class, which tells you what kinds of variables they are. To find out what class a particular variable pertains to, you can use the code: **class(my_variable)**

These are the types of classes available within R:

**"character"**

**"complex"**

**"double"**

**"expression"**

**"integer"**

**"list"**

**"logical"**

**"numeric"**

**"single"**

**"raw"**

**Creating a String**

The character object is used to represent string values in R. To convert objects into character values we would use the **as.character()** function. Here are the string variables in R:

substr(x)

nchar(x)

toupper(x)

tolower(x)

strsplit(x,y)

paste(...)

To create a string in R, you need to first define the variable and relate it to a given function. Then, you specify what data to return when that variable is referenced. Below is an example of a simple string in R that returns randomized capital and lowercase letters as well as numbers using the variable **makerandomstring**.

**Figure 2-4**