ENVS 2100 - post midterm

a collection of lines of code is called…

a script

why code? (3)

• Handles large complex datasets better than many commercial software products (like Excel

• Expands the suite of tools you can use to analyse and visualize data

• Coders / programmers are in demand in the job market. Even if your career isn’t focused entirely on coding, there are many jobs which advertise coding experience as an asset

  or requirement.

why R? (4)

• R is free and open source!

• R provides a wide variety of statistical and graphical techniques.

• R works on data of all shapes and sizes.

• R produces high-quality graphics

• R code (and coding in general) is great for reproducibility

what is the console called?

RGUI

Source Pane

Displays script. Type your code here. Click on Run to execute. Results appear below

Console Pane

Script output is shown here. You can also type code directly (press Return to execute)

Environment/History Pane

Script output is shown here. You can also type code directly (press Return to execute)

Files/Help/Plot Pane

exactly what it says. switch between tabsto access files, help, and plot visualizations.

Variables

used to store data

variablename < -

• must start with a letter or period

• cannot be a reserved word (e.g. TRUE, FALSE, NA)

Operators

arry out different mathematical and logical operations.

• + – * / < > == !=

Functions

execute a specific task. Functions can be built-in, or users can make functions.

• mean() median() sd() var()

• can take multiple arguments within the brakets

Mathematical Operators

+

-

*

/

^ or **

Logical Operators

> greater than

>= greater or equal to

== equal to

!= not equal to

how to make a comment

“#” followed by intended comment

R data types

• numeric

• integer

• double

• character

• logical

numeric data

numbers

integer data

numbers that do not contain decimal values

double data

numbers that contain decimal values

character data

string of keyboard characters (within quotations)

• “hello2you” “3.4”

logical data

truth values

• TRUE or FALSE

how to check the type of data?

use the function: typeof()

reserved words

TRUE = logical value

FALSE = logical value

NA = Not Available, represents a missing value

NaN = Not a number, 0/0

Inf = infinity, 1/0

where are variable stored?

environment

Unlike spreadsheet programs such as Excel, R does not prioritize showing you…

the entire dataset

R data steuctures

• vector

• matrix

• list

• dataframe

vector

Set of elements with the same data type

matrix

2D array of elements with the same data type

list

Set of elements with different data types

dataframe

2D array of elements with different data types

how are excel spreadsheets imported into R?

as dataframes

how to open the Help pane which provides more
information on the function and its arguments?

?functionaname

e.g. breakdown: typeof(x)

• typeof = function

• x = the only argument of the function and is any R object.

• the function returns the data type of x