---
title: "Precept 1"
author: "Emily Nelson"
date: "February 1, 2016"
output: pdf_document
---

Thursday February 4th, 2016
--------------------

# Annoucements

Reorganization of project repositories on GitHub.

#1. Validate set-up (about 20 minutes)

- Open RStudio

- Open an R script

- Talk about 4 panes -- console, files/plots, environment, open file
    * `hist(rnorm(100, 5, 1))` -- show a plot
    * `Control` - `Enter` -- run commands from script window
    * Versus running commands from console
    * Show how variables appear in environment pane

- Install and load libraries -- `load(reshape2)`, display code for `melt`

- **Interlude**: Circulate and answer questions

#2. Basic R Practice (about 30 minutes)

- Type some commands
    * Force interaction here -- start with one person and go around the room
        * Ask general questions like "what is a function?" and specific ones like "what happens if I do this?"

    * Simple math: `4+4`
   
    * Functions: `log(2)`
        * What is a function?
        * Arguments: `log(10, 2)`
        * What does this do differently? What should I add to the above statement to keep up good programming practice?
   
    * Variables: `x <- 2`, `log(x)`
        * `class()` / types of variables
        * We can pass variables to functions: `x <- 2`, `log(x)`
        * what types of variables are in R? (5)
    
    * Vectors and vector-wise functions -- `x <- 1:10`, `log(x)`, `sum(x)` -- see the difference?
        * Creating a vector -- `c()`, `vector()`
        * Subsetting a vector
        
    * Matrices
        * Create a matrix -- `matrix()`
        * What happens when we use functions on matrices?
        
    * Factors
        * Why / when would we want to use factors?
    
    * Lists
        * What is the difference between vectors and lists?
        * `[]` versus `[[]]`
    
    * Make a `data.frame` -- or maybe just load `mtcars` and look at it
        * Extract a column -- `mtcars$mpg` -- What is this?
        * We can use functions on this too
    
- **Interlude**: Circulate and answer questions

#3. Corresponding R Code

```{r code}
4 + 4

log(2)

log(10, base=2)

x <- 2

log(x)

class(x)

y <- 1:10

log(y)

sum(y)

m <- matrix(1:6, nrow=2)

sum(m)

log(m)

colSums(m)

rowSums(m)

data(mtcars)

head(mtcars)

class(mtcars)

mtcars$mpg

class(mtcars$mpg)

mean(mtcars$mpg)
```