# Progress Log 103 (R): The True Basics

- May 29, 2019
- nanakoohashi
- Data Analytics/Data Science, R
- No Comments

#### I’m taking an edX course entitled “Introduction to R for Data Science” and all of the concepts described below come from that course.

**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**

- 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.
**Creating variables:**You use the less than followed by a dash to create a variable.- <-

**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**

- 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.
**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()`

- If we try to print out a non-exiting variable, for example, depth. R throws an error.
- 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`

- 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`

- If you now type area, you’ll see that it contains 8 as well.
- 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.

** Comments **

- To comment, you start with the pound sign
`#`

followed by the comment.

**Cleaning up your workspace**

- 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.