Packages
Are you struggling?
Plan for today
- Brief recap
- Packages
Recap of using variables
- Most of the time, we want to do more than add, subtract, multiply etc.
Recap of using variables
Most of the time, we want to do more than add, subtract, multiply etc.
We want to act on our variables. We do this with operators & functions
- Each function has a unique name
- Each function requires some input, and the function can be modified using arguments
- Each function will produce an output
Recap of using variables
Most of the time, we want to do more than add, subtract, multiply etc.
We want to act on our variables. We do this with operators & functions
- Each function has a unique name
- Each function requires some input, and the function can be modified using arguments
- Each function will produce an output
Remember:
- objects are nouns
- functions & operators are verbs
- arguments are adverbs
Recap of using variables
Where do you find functions?
- Some exist in
Rby defaultt.test()cor()scale()
Lots of people all over the world write their own functions. And they (rightly!) think it's useful to share these functions.
Packages
What is a package?
- A collection of functions and datasets
- Open source
Packages are the reason R is so powerful!
- While you can definitely write your own functions, most of what you need to do someone else has already done for you!
How do I get packages?
Packages can be downloaded from the CRAN (Comprehensive R Archive Network)
You will do this from inside R
Need to be connected to the internet!
2 ways to install packages
Install button in the Packages tab
R Code
Either way, you need to know the name of the package
Install Button
Install Button
Install Button
R code to install packages
install.packages("psych")
Packages
INSTALLING
- Downloading the package and saving it to your computer
- Like installing Microsoft Word on your computer
- Do this ONCE
Packages
INSTALLING
- Downloading the package and saving it to your computer
- Like installing Microsoft Word on your computer
- Do this ONCE
LOADING
- Like opening Microsoft Word to write a paper
- Once a package is loaded, you can use all of it's functions and datasets are ready to use
- You need to do this EVERY TIME you open a new
Rsession
2 ways to load packages
Checkbox in the packages tab (not recommended)
R code
Either way, you need to know the name of the package
R code to load packages
library(psych)
Dependencies
Uses functions from other packages
Installed automatically
Loaded automatically
Help! (again)
Ways to find documentation:
?psych -- opens documentation specific to that pacakge or function
??psych -- searches for this in all documentation (that you have installed and loaded)
To find a package that does what you need: Google
Summary
Packages are a collection of functions and data sets
- You install the package once; must be connected to the internet
- You load the package every time you use it; do not need to be connected to the internet
Summary
Packages are a collection of functions and data sets
- You install the package once; must be connected to the internet
- You load the package every time you use it; do not need to be connected to the internet
How do you find the function you need? How do you now what package it's in?
- G-o-o-g-l-e!
- "structural equation modeling in R"
Summary
Packages are a collection of functions and data sets
- You install the package once; must be connected to the internet
- You load the package every time you use it; do not need to be connected to the internet
How do you find the function you need? How do you now what package it's in?
- G-o-o-g-l-e!
- "structural equation modeling in R"
How do you know how to use the function? What are the function's arguments?
- Help documentation in R
? function.name