---
title: "Packages"
author: "Russell Almond"
date: "February 1, 2019"
output: ioslides_presentation
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = FALSE)
```

## R Packages

Packages add new capabilities to R.

Package contains:
- DESCRIPTION -- Name, short description, version, dependencies
- R code 
- Man pages (help) for new code

Package may also contain:
- SRC:  C, Fortran, Java, ... code to add functionality or to link to other tools (e.g., a database)
- Data:  Sample data to test functions
- Vingettes:  Longer narrative help that describes how to do something.

## Finding new R packages

- CRAN: Comprehensive R Archive Network
  + >13,000 packages:  https://cran.r-project.org/
  + Mirrors around the world https://cloud.r-project.org/
- GitHub:  Many package sources are maintained there.
- Private Repositories
- Search Stack Overflow and similiar sites.

## Three Steps -- Download, Install and Load

1. First, you must download the package code (either source or compiled to your computer)
2. Then the package must be _installed_ in a library directory that R knows about.  
  + The `install.packages(name)` function will do steps 1 and 2
3. When you want to use functions from the package, you need to _load_ them into the workspace.  
  + This can be done with `library(name)` or `require(name)`.


## Slide with Bullets

- Bullet 1
- Bullet 2
- Bullet 3

## Slide with R Output

```{r cars, echo = TRUE}
summary(cars)
```

## Slide with Plot

```{r pressure}
plot(pressure)
```