Intro to R

# Intro to R
### Intro to Data Science with R <a href='https://therbootcamp.github.io'> The R Bootcamp @ Unibe </a> <a href='https://dwulff.github.io/Intro2R_Unibe_2021/'> </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>
### September 2021

---

<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/">
 
 The R Bootcamp | September 2021
 
 </a>
 
 </div>

---

# R is a programming language

From [Wikipedia](https://en.wikipedia.org/wiki/Statistical_model) (emphasis added):

> A programming language is a **formal language** that specifies a set of instructions that can be used to produce various kinds of output. Programming languages generally consist of **instructions for a computer**. Programming languages can be used to create programs that **implement specific algorithms**.

```r
data <- read.table("data/my_data.txt")
variables <- data[,c('group','variable')]
analysis <- lm(variable ~ group, data = variables)
summary(analysis)
```
]

---

# Why R?

Today, R is one of the **most popular languages for data science** and overall.

In terms of the number of data science jobs, **R beats SAS and Matlab**, and is on par with Python.

In many sciences it becomes the de factor **lingua franca** for statistics.

Image source: http://r4stats.com/blog/

]

.pull-right6[

 <img src="https://i0.wp.com/r4stats.com/wp-content/uploads/2017/02/Fig-1a-IndeedJobs-2017.png" height="450">

]

---

# Tidyverse

<ul>
 <li class="m1">The tidyverse is...</li> 
 <ul class="level">
 <li>A collection of user-friendly <high>packages</high> for analyzing <high>tidy data</high></li> 
 <li>An <high>ecosystem</high> for analytics and data science with common design principles</li> 
 <li>A <high>dialect</high> of the R language</li>
 </ul>
</ul>

]

---

# Tidyverse

]

---

# RStudio

<ul>
 <li class="m1">RStudio is...</li> 
 <ul class="level">
 <li>A high-productivity <high>data science IDE.</high></li> 
 <li>The <high>company</high> behind the tidyverse.</li> 
 <li>Designed for R tidyverse with <high>good integration</high> for Python, Markdown, or C++.</li> 
 </ul>
</ul>

]

---

<div class="center_text">
 
 Intro 2 Base R
 
</div>

---

# Part 1: Assignments

<ul>
 <li class="m1"><high>Assignments</high> </li>
 <ul class="level">
 <li>Object <mono><-</mono> function</li>
 <li><mono><-</mono> creates objects</li>
 <li><mono><-</mono> changes objects</li>
 </ul>
 
 <li class="m2g">Functions</li>
 <li class="m3g">Pipes</li>
</ul>

]

.pull-right5[
 

<img src="image/goodcode.png" height=500px> 
from <a href="https://xkcd.com//">xkcd.com</a>

]

---

# Object <mono><-</mono> function

<ul>
 <li class="m1">Assignments </li>
 <ul class="level">
 <li><high>Object <mono><-</mono> function</high></li>
 <li><mono><-</mono> creates objects</li>
 <li><mono><-</mono> changes objects</li>
 </ul>
 
 <li class="m2g">Functions</li>
 <li class="m3g">Pipes</li>
</ul>

]

]

---

# <mono><-</mono> creates objects

<ul>
 <li class="m1">Assignments </li>
 <ul class="level">
 <li>Object <mono><-</mono> function</li>
 <li><high><mono><-</mono> creates objects</high></li>
 <li><mono><-</mono> changes objects</li>
 </ul>
 
 <li class="m2g">Functions</li>
 <li class="m3g">Pipes</li>
</ul>

]

```r
# an object named one_two_three
one_two_three <- c(1, 2, 3)

# print the object
print(one_two_three)
```

```
[1] 1 2 3
```

```r
# print the object
one_two_three
```

```
[1] 1 2 3
```

]

---

# <mono><-</mono> creates objects

]

```r
# an object named one_two_three
one_two_three <- c(1, 2, 3)

# calculate the mean
mean(one_two_three)
```

```
[1] 2
```

]

---

# <mono><-</mono> creates objects

]

```r
# an object named one_two_three
one_two_three <- c(1, 2, 3)

# calculate the mean
result <- mean(one_two_three)

# print result
result
```

```
[1] 2
```

]

---

# <mono><-</mono> creates objects

]

```r
# an object named one_two_three
one_two_three <- c(1, 2, 3)

# calculate the mean
result <- mean(one_two_three)

# use result
result * 10
```

```
[1] 20
```

]

---

# <mono><-</mono> changes objects

<ul>
 <li class="m1">Assignments </li>
 <ul class="level">
 <li>Object <mono><-</mono> function</li>
 <li><mono><-</mono> creates objects</li>
 <li><high><mono><-</mono> changes objects</high></li>
 </ul>
 
 <li class="m2g">Functions</li>
 <li class="m3g">Pipes</li>
</ul>

]

```r
# an object named one_two_three
one_two_three <- c(1, 2, 3)

# print the object
one_two_three
```

```
[1] 1 2 3
```

```r
# use the object
one_two_three + 100
```

```
[1] 101 102 103
```

```r
# print the object
one_two_three
```

```
[1] 1 2 3
```

]

---

# <mono><-</mono> changes objects

]

```r
# an object named one_two_three
one_two_three <- c(1, 2, 3)

# print the object
one_two_three
```

```
[1] 1 2 3
```

```r
# use the object
one_two_three <- one_two_three + 100

# print the object
one_two_three
```

```
[1] 101 102 103
```

]

---

# Part 2: Functions

<ul>
 <li class="m1g">Assignments </li>
 <li class="m2"><high>Functions</high></li>
 <ul class="level">
 <li>Everything happens using functions</li>
 <li>Functions have (default) arguments</li>
 <li>The class of functions matters</li>
 <li>Functions "live" in packages</li>
 <li>Receive help using <mono>?</li>
 </ul> 
 <li class="m3g">Pipes </li>
</ul>

]

]

---

# Functions

---

# Functions

.pull-left4[
<ul>
 <li class="m1g">Assignments </li>
 <li class="m2">Functions</li>
 <ul class="level">
 <li><high>Everything happens using functions</high></li>
 <li>Functions have (default) arguments</li>
 <li>The class of functions matters</li>
 <li>Functions "live" in packages</li>
 <li>Receive help using <mono>?</li>
 </ul> 
 <li class="m3g">Pipes </li>
</ul>
]

```r
# function c()
one_two_three <- c(1, 2, 3)

# function `+`()
one_two_three + 100
```

```
[1] 101 102 103
```

```r
# function print()
one_two_three
```

```
[1] 1 2 3
```

```r
# function mean()
mean(one_two_three)
```

```
[1] 2
```
]

---

# Arguments

.pull-left4[
<ul>
 <li class="m1g">Assignments </li>
 <li class="m2">Functions</li>
 <ul class="level">
 <li>Everything happens using functions</li>
 <li><high>Functions have (default) arguments</high></li>
 <li>The class of functions matters</li>
 <li>Functions "live" in packages</li>
 <li>Receive help using <mono>?</li>
 </ul> 
 <li class="m3g">Pipes </li>
</ul>
]

```r
# no argument
mean()
```

```
Error in mean.default(): argument "x" is missing, with no default
```

```r
# one (necessary) argument
mean(c(1, 2, 3))
```

```
[1] 2
```

```r
# add missing value (NA)
mean(c(1, 2, 3, NA))
```

```
[1] NA
```
]

---

# Arguments

```r
# no argument
mean()
```

```
Error in mean.default(): argument "x" is missing, with no default
```

```r
# one (necessary) argument
mean(c(1, 2, 3))
```

```
[1] 2
```

```r
# change default to remove NAs
mean(c(1, 2, 3, NA), na.rm = TRUE)
```

```
[1] 2
```
]

---

# Arguments

```r
# explicit argument names
mean(x = c(1, 2, 3, NA), na.rm = TRUE)
```

```
[1] 2
```

```r
# with names order does not matter
mean(na.rm = TRUE, x = c(1, 2, 3, NA))
```

```
[1] 2
```

```r
# without names order matters
mean(TRUE, c(1, 2, 3, NA))
```

```
Error in mean.default(TRUE, c(1, 2, 3, NA)): 'trim' must be numeric of length one
```
]

---

# Classes

.pull-left4[
<ul>
 <li class="m1g">Assignments </li>
 <li class="m2">Functions</li>
 <ul class="level">
 <li>Everything happens using functions</li>
 <li>Functions have (default) arguments</li>
 <li><high>The class of functions matters</high></li>
 <li>Functions "live" in packages</li>
 <li>Receive help using <mono>?</li>
 </ul> 
 <li class="m3g">Pipes </li>
</ul>
]

]

---

# Classes

.pull-left4[
<ul>
 <li class="m1g">Assignments </li>
 <li class="m2">Functions</li>
 <ul class="level">
 <li>Everything happens using functions</li>
 <li>Functions have (default) arguments</li>
 <li><high>The class of functions matters</high></li>
 <li>Functions "live" in packages</li>
 <li>Receive help using <mono>?</li>
 </ul> 
 <li class="m3g">Pipes </li>
</ul>
]

```r
# calculate mean of c(1, 2, 3)
mean(c(1, 2, 3))
```

```
[1] 2
```

```r
# calculate mean of c('1', '2', '3')
mean(c("1", "2", "3"))
```

```
Warning in mean.default(c("1", "2", "3")): argument is not numeric or logical: returning NA
```

```
[1] NA
```
]

---

# Classes

.pull-left4[
<ul>
 <li class="m1g">Assignments </li>
 <li class="m2">Functions</li>
 <ul class="level">
 <li>Everything happens using functions</li>
 <li>Functions have (default) arguments</li>
 <li><high>The class of functions matters</high></li>
 <li>Functions "live" in packages</li>
 <li>Receive help using <mono>?</li>
 </ul> 
 <li class="m3g">Pipes </li>
</ul>
]

```r
# calculate sum of c(1, 2, 3)
sum(c(1, 2, 3))
```

```
[1] 6
```

```r
# calculate sum of c('1', '2', '3')
sum(c("1", "2", "3"))
```

```
Error in sum(c("1", "2", "3")): invalid 'type' (character) of argument
```
]

---

# Packages

.pull-left4[
<ul>
 <li class="m1g">Assignments </li>
 <li class="m2">Functions</li>
 <ul class="level">
 <li>Everything happens using functions</li>
 <li>Functions have (default) arguments</li>
 <li>The class of functions matters</li>
 <li><high>Functions "live" in packages</high></li>
 <li>Receive help using <mono>?</li>
 </ul> 
 <li class="m3g">Pipes </li>
</ul>
]

---

# Packages

.pull-left4[
<ul>
 <li class="m1g">Assignments </li>
 <li class="m2">Functions</li>
 <ul class="level">
 <li>Everything happens using functions</li>
 <li>Functions have (default) arguments</li>
 <li>The class of functions matters</li>
 <li><high>Functions "live" in packages</high></li>
 <li>Receive help using <mono>?</li>
 </ul> 
 <li class="m3g">Pipes </li>
</ul>
]

<high>Install</high> Packages <high>once</high> with `install.packages()`

```r
install.packages("tidyverse")
```
<br2>
<high>Load</high> installed Pakete <high>every time</high> with `library()`

```r
library(tidyverse)
```

<img src="image/tidyverse_load.png" height="180">
]
---

# Help

.pull-left4[
<ul>
 <li class="m1g">Assignments </li>
 <li class="m2">Functions</li>
 <ul class="level">
 <li>Everything happens using functions</li>
 <li>Functions have (default) arguments</li>
 <li>The class of functions matters</li>
 <li>Functions "live" in packages</li>
 <li><high>Receive help using <mono>?</high></li>
 </ul> 
 <li class="m3g">Pipes </li>
</ul>
]

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

---

# Part 3: Pipes

.pull-left4[
<ul>
 <li class="m1g">Assignments </li>
 <li class="m2g">Functions </li>
 <li class="m3"><high>Pipes</high> </li>
 <ul class="level">
 <li>Swap object and function</li>
 <li>Make chaining easy</li>
 </ul>
</ul>
]

<img src="image/magrittebrother.jpeg" height=400px> 
from <a href="https://knowyourmeme.com/photos/1217327-this-is-not-a-pipe-parodies">knowyourmeme.com</a>

]

---

# Pipes

.pull-left4[
<ul>
 <li class="m1g">Assignments </li>
 <li class="m2g">Functions </li>
 <li class="m3">Pipes </li>
 <ul class="level">
 <li><high>Swap object and function</high></li>
 <li>Make chaining easy</li>
 </ul>
</ul>
]

```r
# Numeric vector
score <- c(8, 4, 6, 3, 7, 3)
score
```

```
[1] 8 4 6 3 7 3
```

```r
# Mean: Base-R-style
mean(score)
```

```
[1] 5.167
```

```r
# Mean: dplyr-style
score %>%  
  mean()  
```

```
[1] 5.167
```
]

---

# Pipes

]

---

# Pipes

.pull-left4[
<ul>
 <li class="m1g">Assignments </li>
 <li class="m2g">Functions </li>
 <li class="m3">Pipes </li>
 <ul class="level">
 <li>Swap object and function</li>
 <li><high>Make chaining easy</high></li>
 </ul>
</ul>
]

```r
# Numeric vector
score <- c(8, 4, 6, 3, 7, 3)
score
```

```
[1] 8 4 6 3 7 3
```

```r
# Chainig
score %>%  
  mean() %>% 
  round(digits = 2)
```

```
[1] 5.17
```
]

---

# Pipes

.pull-left4[
<ul>
 <li class="m1g">Assignments </li>
 <li class="m2g">Functions </li>
 <li class="m3">Pipes </li>
 <ul class="level">
 <li>Swap object and function</li>
 <li><high>Make chaining easy</high></li>
 </ul>
</ul>
]

```r
# Numeric vector
score <- c(8, 4, 6, 3, 7, 3)
score
```

```
[1] 8 4 6 3 7 3
```

```r
# Chainig
score %>%  
  mean() %>% 
  round(digits = 2) %>% 
  as.character()
```

```
[1] "5.17"
```
]

---

<h1><a>Interactive</a></h1>
<h2>Open the TheRBootcamp project file</h2>