Recap I

# Recap I
### Introduction to R <a href='https://therbootcamp.github.io'> Bern R Bootcamp </a> <a href='https://dwulff.github.io/Intro2R_Unibe/'> </a>  <a href='https://therbootcamp.github.io'> </a>  <a href='mailto:therbootcamp@gmail.com'> </a>  <a href='https://www.linkedin.com/company/basel-r-bootcamp/'> </a>
### June 2020

---

<div class="my-footer">
 
 
 <img src="https://raw.githubusercontent.com/therbootcamp/therbootcamp.github.io/master/_sessions/_image/by-sa.png" height=14 style="vertical-align: middle"/>
 
 <a href="https://therbootcamp.github.io/">
 
 
 www.therbootcamp.com
 
 
 </a>
 <a href="https://therbootcamp.github.io/">
 
 R Bootcamp Bern | June 2020
 
 </a>
 
 </div>

---

# Essentials: 12 basic R lessons

.pull-left4[
1. Everything is an object
2. Use `<-` to create/change objects
3. Name objects using `_`
4. Objects have classes
5. Everything happens through functions
6. Functions have (default) arguments
7. Functions expect certain object classes
8. View help files using `?`
9. Study errors and warnings
10. Use RStudio and projects
11. Use editor and auto-complete
12. Comment and format for readability
]

---

# 3 Object types for data

R has 3 main data objects...

<high>`list`</high> - R's multi-purpose container
- Can carry any data, incl. lists
- Often used for function outputs

<high>`tibbles`</high> - R's spreadsheet
- Specific type of `list`
- Typical data format
- For multi-variable data sets

<high>`vectors`</high> - R's data container
- Actually carries the data
- Contain data of 1 of many types

]

.pull-right55[
<img src="https://raw.githubusercontent.com/therbootcamp/therbootcamp.github.io/master/_sessions/_image/main_objects.png"></img>
]

---

# Documentation

R documentation (<high>help files</high> and <high>vignettes</high>) will become very to use once you are familiar with the basic R vocabulary.

Pay attention to...

<high>Usage</high> - shows how to use function, its arguments and their defaults. <high>Arguments</high> - describes arguments, and their `class`. <high>Value</high> - describes what the function returns. <high>Examples</high> - provide working R code.

```r
# To access help files
?name_of_function

# search help files
??name_of_function
```

]

```r
?cor
```
<img src="https://raw.githubusercontent.com/therbootcamp/therbootcamp.github.io/master/_sessions/_image/help_cor.png" width="500">
]

---

# Data Input/Output

Raw data can come in many shapes and sizes, but <high>R's got you covered</high>.
 
.pull-left65[

| Package     |   Description|
|:----------------|:-------------------------------------------------------|
| `readr`| `.csv`, `.txt`, etc. |
| `haven`| `.sav`, `.sas7bdat`, `.dta`          |
| `readxl`  | `.xls`, `.xlsx` |
| `R.matlab` | `.mat` |
| `jsonlite` | `.json` |
| `rvest` | `.html` |
| `XML`, `xml2` | `.xml` |

]

]
---

# Finding the file path

1 - Identify the file path using the <high>auto-complete</high>.

2 - Initiate auto-complete and browse through the folder structure by placing the cursor between two quotation marks and using the <high>tab key</high>.

3 - Auto-complete begins with the project folder - <high>place your data inside your project folder!</high>

]

]

---
.pull-left45[

# What is wrangling?

<high>Transform</high>

Change column names

Add new columns

<high>Organise</high>

Sort data by columns

Merging data from two separate dataframes

Move data between columns and rows

<high>Aggregate</high>

Group data and summarise
]

.pull-right5[
 

 <img src="https://raw.githubusercontent.com/therbootcamp/therbootcamp.github.io/master/_sessions/_image/organise_transform_aggregate.png" height = "550px">

]

---

# The Pipe! <high>`%>%`</high>

`dplyr` makes extensive use of a new operator called the "Pipe" <high>`%>%`</high>

Read the "Pipe" <high>`%>%`</high> as "And Then..."

```r
# Start with data
data %>% # AND THEN...
  
DO_SOMETHING %>% # AND THEN...
  
DO_SOMETHING %>% # AND THEN...
  
DO_SOMETHING %>% # AND THEN...
```

]

<img src="https://upload.wikimedia.org/wikipedia/en/thumb/b/b9/MagrittePipe.jpg/300px-MagrittePipe.jpg" width = "450px"> 
 This is not a pipe (but %>% is!)

]

---

<h1><a href="https://dwulff.github.io/Intro2R_Unibe/1_Data/BernRBootcamp_Day2.zip">Downloads</a></h1>

---

<hfont><high>Questions?</high></hfont> 
 <a href = "https://therbootcamp.github.io/Intro2DataScience_2018Oct/">Link to schedule</a>

]

]