presentation.Rmd

---
title: "R, y u do dis?"
author: Christoph Molnar
date: February 6, 2017
output: ioslides_presentation
widescreen: false
---

## R can be rewardingly easy to use
<img src="./img/ez.gif" width="600px" />

## R can be also a source of frustration
<img src="./img/code-not-working.gif" width="800px" />

## Let's do some simple calculations 
```{r, results='hide'}
options(digits=22)

1.1 - 0.2
```

## Let's do some simple calculations 
```{r}
options(digits=22)

1.1 - 0.2
```

## Let's do some simple calculations 
<img src="./img/wat.jpg" width="800px" />

## Let's do some simple calculations 
```{r}
options(digits=22)

1.1 - 0.2
```
Reason: Machine representation of float (numbers with decimal points)

## Usually differences are negligibly small
<img src="./img/small.jpg" width="800px" />


## Let's talk about any() and all()
```{r, results='hide'}
all(c())
any(c())
```

## Let's talk about any() and all()
```{r}
any(c())
```

## Let's talk about any() and all()
```{r}
all(c())
```
<img src="./img/arbitrary.jpg" width="500px" />

## Let's talk about any() and all()
Solution in the help file: 
<img src="./img/all.png" width="800px" />

## Factors are super useful!
<img src="./img/gadget.jpg" width="800px" />

## Working with factors in R
```{r}
dat <- data.frame(measure = c('6','1', '1', '1', '2','10','4'))
as.numeric(dat$measure)
```

## Working with factors in R
```{r}
str(dat$measure)
```


## R is full of (implicit) coercion
<img src="./img/unexpected.gif" width="800px" />

## Implicit coercions is implicit!
```{r}
dat$measure
c(dat$measure, c(22, 1))
```


## Working with factors in R
<img src="./img/factor.png" width="800px" />


## require('bananas') vs library('bananas')
```{r, eval=FALSE}
require('bananas')
library('bananas')
```

## require('bananas') vs library('bananas')
```{r, error=TRUE}
require('bananas')
library('banana')
```
=> Use library in most cases

## require('bananas') vs library('bananas')
```{r, warning=FALSE, message=FALSE}
x <- require('bananas')
x
```

```{r, eval=FALSE}
if(!x){
  install.packages('banana')
}
```

## require('bananas') vs library('bananas')
<img src="./img/banana.jpg" width="400px" />


## <- vs = 
```{r}
x <- 1
x = 1
```
What's the difference?


## <- vs = 
In practice same functionality. 

```{r}
mean(new_var <- c(1,2))
new_var
```
## What about <<- ?
```{r}
var = 1
fun = function(x){var <<- x}
fun(2)
var
```
<img src="./img/fire.gif" width="300px" />

## Some advice
- R help is helpful, use it!
- Nice FAQ!

## Meta facts about the talk:

- Slides down with knitr+RMarkdown+ioslides
- Slides on Github: https://github.com/christophM/r-y-u-do-dis
- Time spent: 
    - 20% on content and practicing
    - 80% on choosing the memes

# Thanks!