# Progress Log 103 (R): The True Basics

### Console

• Basic Arithmetic. We can calculate the sum of 1 and 2 by simply typing 1 + 2 in the console and hitting enter.
• `1 + 2`
• Text: We can type text in the console by using double quotes and then hitting enter.
• `"Hi there, console!"`

### Variable

1. A variable allows you to store a value or an object in R. You can use this variable’s name to easily access the value or the object that is stored within this variable.
2. Creating variables: You use the less than followed by a dash to create a variable.
• <-
3. Assigning variables: Suppose the number 2 is the height of a rectangle and 4 is the width. Let’s assign this value 2 to the variable ‘height’ and 4 to the variable of ‘width’.
• `height <- 2`
• `width <- 4`

### Workspace

1. As you’re assigning variables in the R console, you’re actually accumulating an R workspace. It’s the place where variables and information are stored in R.
2. Accessing objects in the workspace: You use the function ls() to show you a list of variables you have created in the R session.
• `ls()`
3. If we try to print out a non-exiting variable, for example, depth. R throws an error.
4. The principle of accumulating a workspace through variable assignment makes these variables available for further use. Suppose we want to find out the area of our imaginary rectangle, we can calculate the area as follows:
• `height * width`
5. The result is 8 as you would expect. We can take this one step further and also assign the result of this calculation to a new variable, area.
• `area <- height * width`
6. If you now type area, you’ll see that it contains 8 as well.
7. Inspecting the workspace again with `ls`, you can see that the workspace contains three objects now: area, height, and width.

### R script

• An R script is a text file containing a collection of successive lines of R code that solve a particular task. When using R, you will build a lot of scripts to make things easier for you, and hopefully automate parts of your work.

• To comment, you start with the pound sign `#` followed by the comment.

• Use `rm()` to remove variables from your workspace.
• `rm(area)`

#### Arithmetic

In its most basic form R can be used as a simple calculator. Consider the following arithmetic operators:

• Addition: `+`
• Subtraction: `-`
• Multiplication: `*`
• Division: `/`
• Exponentiation: `^`
• Modulo: `%%`

The last two might need some explaining:

• The ^ operator raises the number to its left to the power of the number to its right: for example, 3^2 equals 9.
• The modulo returns the remainder of the division of the number to the left by the number on its right, for example, 5 modulo 3 or `5 %% 3` equals 2.