getting_started.Rmd

---
title: "Getting Started with R"
author: "Tony Yao-Jen Kuo"
output: 
  revealjs::revealjs_presentation:
    highlight: pygments
    reveal_options:
      slideNumber: true
      previewLinks: true
---

```{r include=FALSE}
knitr::opts_chunk$set(results = "hold")
```

# Getting Started

## The characteristics of R

- Comparing to Matlab, SAS, SPSS: Free
- Comparing to Julia: Larger community
- Functional Programming

## R in one sentence

> Applying functions to objects.

## R: core of computation

- Download from <https://cran.r-project.org/>

![](https://i.imgur.com/A5OwsnX.png)

## RStudio: the IDE

- Download from <https://www.rstudio.com/products/rstudio/download>

# Interface of RStudio

## Four blocks

- Script
- Console
- Environment
- Multi-functional

## Console tricks

- Using `Ctrl + L` for clearing
- Using Up and Down arrow checking executed scripts

## Keyboard shortcuts

- Using `Alt + Shift + K` for shortcuts

# Quickstart

## Using `<-` for assignment

- `=` is OKAY, but `<-` is more common
- Using `Alt + -` to get `<-`

## Using `#` for comments

```{r}
# Declaring objects

# Declaring function

```

## Assignments in action

```{r}
# Declaring objects
my_favorite_star <- "Tom Cruise"
my_lucky_number <- 24
r_is_easy <- TRUE

# Declaring function
say_hello <- function(){
  return("Hello R!")
}
```

## Printing objects or calling function

```{r results='hold'}
# Printing objects
my_favorite_star
my_lucky_number
r_is_easy

# Calling function
say_hello()
```

## Using `rm()` to remove objects

```{r eval=FALSE}
rm(r_is_easy)
r_is_easy # Error
```

## Why is R Console showing `+`?

- The reason is that R is still expecting inputs from us

```{r eval=FALSE}
my_favorite_player <- "Steve Nash

say_hello <- function(){
  return("Hello R!")

help(print
```

## 2 ways to solve it

1. Complete your inputs
2. ESC

## Install packages

- `install.packages()`
- Do it once

## Library packages

- `library()`
- Do it every time

# Useful functions

## Function to query functions or data

```{r eval=FALSE}
help(print) # ?print
help(cars) # ?cars
```

## Function to show relative information

```{r}
sessionInfo()
```

## Function to get locale

```{r}
Sys.getlocale()
```

## Function to get current working directory

```{r}
getwd()
```

## Function to set working directory

- Always use forward slash when declaring path
- Back slash has other functionalities, such as escape, Unicode...
- Try not to use non-English username

```{r eval=FALSE}
setwd("/Users/USERNAME/Desktop") # MacOS desktop
setwd("C:/Users/USERNAME/Desktop") # Windows desktop
```

## Function to quit RStudio

- Not saving workspace image is recommended

```{r eval=FALSE}
q()
```

## Common learning path for programming

- Installation of compiler or interpreter
- Choosing a friendly IDE
- Quickstart
- Variable types
  - Functions
  - Control flows
- Data structure
  - Iterations
- (Optional) Class
- (Optional) Package development