Introduction

R works by running functions that live within packages. To use these packages, we must install them and load them whenever we open or restart R. Here, I will show how to install/load packages and have you install 3 of my favorite packages.

Installing Packages

We need to install packages before we can use them. I will use the tidyverse package as an example (it’s my favorite package). To install packages you will run this code (by removing the hashtag in front of the “install.packages” function).

# install.packages("tidyverse") 
# function is "install.packages"
# argument is "tidyverse" AKA the name of the package in quotation marks

Packages only need to be installed once, so after installing code, you want to comment out the code by placing a hashtag in front of the code. This stops the line of code from running.

You can also include a conditional install in your code so that you do not have to comment out your code. This code does the following:
* Creates a list of the packages that will be used in the script
* For each of the packages in the script, it searches for the name of the package in the list of the installed packages
* If the package does not exist in the list, it installs it, otherwise it does nothing

requiredPackages = c('tidyverse', 'here', 'janitor') #create a list of the packages to conditionall install

for(p in requiredPackages){ # for each of the packages (we'll call this "p") in the list above (requiredPackages), do the following:
  
  if(!require(p,character.only = TRUE)) install.packages(p) # if the package is not in the list of installed packages, install the package, or else do not install the package
}

Loading libraries

To load libraries, run the following code:

library(tidyverse)

# library() is the function
# tidyverse is the argument AKA the name of the package. It does not need to be in quotations because it is already installed in the packages

We do not need to comment out the lines that load the libraries/packages because they need to be ran everytime R is restarted.

We can now add on to our conditional install code from above, telling it to then load all packages.

requiredPackages = c('tidyverse', 'here', 'janitor') #create a list of the packages to conditionall install

for(p in requiredPackages){ # for each of the packages (we'll call this "p") in the list above (requiredPackages), do the following:
  
  if(!require(p,character.only = TRUE)) install.packages(p) # if the package is not in the list of installed packages, install the package, or else do not install the package

  library(p,character.only = TRUE) # we add this line of code and it loads all the packages
  
}

Please run the conditional install code above in your own R to install my favorite packages that we will be using, tidyverse, here, and janitor.

Thank you and please continue on to the next section to learn more :)

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