Introduction to ggplot

<br>
<br>
.right-panel[

# Introduction to ggplot
## Dr. Mine Dogucu
]

---

- This specific lecture will not necessarily show you beautiful plots.

- In this lecture we will focus on how ggplot works.

- In the next lecture we will improve the plots that we make.

---

center: invisible

__gg__plot is based on __g__rammar of __g__raphics.

---

## Data

```r
glimpse(titanic)
```

```
## Rows: 891
## Columns: 6
## $ survived <lgl> FALSE, TRUE, TRUE, TRUE, FALSE, FALSE, FALSE, FALSE, TRUE, T…
## $ pclass   <chr> "Third", "First", "Third", "First", "Third", "Third", "First…
## $ sex      <fct> sex, sex, sex, sex, sex, sex, sex, sex, sex, sex, sex, sex, …
## $ age      <dbl> 22, 38, 26, 35, 35, NA, 54, 2, 27, 14, 4, 58, 20, 39, 14, 55…
## $ fare     <dbl> 7.2500, 71.2833, 7.9250, 53.1000, 8.0500, 8.4583, 51.8625, 2…
## $ embarked <fct> Southampton, Cherbourg, Southampton, Southampton, Southampto…
```

---

class:inverse middle

---

**3 Steps of Making a Basic ggplot**

1.Pick data

2.Map data onto aesthetics

3.Add the geometric layer

---
class: middle

### Step 1 - Pick Data

```r
ggplot(data = titanic)
```
]

![](03b-intro-ggplot_files/figure-html/unnamed-chunk-5-1.png)

]

---

### Step 2 - Map Data to Aesthetics

```r
ggplot(data = titanic,
*      aes(x = pclass))
```
]

![](03b-intro-ggplot_files/figure-html/unnamed-chunk-7-1.png)

]

---

### Step 3 - Add the Geometric Layer

```r
ggplot(data = titanic,
       aes(x = pclass)) +
* geom_bar()
```
]

![](03b-intro-ggplot_files/figure-html/unnamed-chunk-9-1.png)
]
---

.panel[
.panel-name[Plot]
<img src="03b-intro-ggplot_files/figure-html/unnamed-chunk-10-1.png" style="display: block; margin: auto;" />

]

- Create a ggplot using the `titanic` data frame.
- Map the `fare` to the x-axis. 
- Add a layer of a bar plot.

]

```r
ggplot(data = titanic,
       aes(x = pclass)) +
  geom_bar()
```

]

]
---

class:inverse middle

---

```
## `stat_bin()` using `bins = 30`. Pick better value with `binwidth`.
```

]

- Create a ggplot using the `titanic` data frame.
- Map the `fare` to the x-axis. 
- Add a layer of a histogram.

]

```r
ggplot(data = titanic,
       aes(x = fare)) +
  geom_histogram() 
```

]

---
class: middle

### Step 1 - Pick Data

```r
ggplot(data = titanic)
```
]

![](03b-intro-ggplot_files/figure-html/unnamed-chunk-15-1.png)

]

---

### Step 2 - Map Data to Aesthetics

```r
ggplot(data = titanic,
*      aes(x = fare))
```
]

![](03b-intro-ggplot_files/figure-html/unnamed-chunk-17-1.png)

]

---

### Step 3 - Add the Geometric Layer

```r
ggplot(data = titanic,
       aes(x = fare)) +
* geom_histogram()
```
]

```
## `stat_bin()` using `bins = 30`. Pick better value with `binwidth`.
```

![](03b-intro-ggplot_files/figure-html/unnamed-chunk-19-1.png)
]

---

## What is this warning?

```
## `stat_bin()` using `bins = 30`. Pick better value with `binwidth`.
```

---

```r
ggplot(data = titanic,
       aes(x = fare)) +
* geom_histogram(binwidth = 15)
```

---

]

]

]

]

---

[There is no "best" number of bins](https://en.wikipedia.org/wiki/Histogram#Number_of_bins_and_width)

---

Pick your favorite color(s) from the list at:

[bit.ly/colors-r](https://bit.ly/colors-r)

---

```r
ggplot(data = titanic,
       aes(x = fare)) +
  geom_histogram(binwidth = 15, 
*                color = "white")
```

---

```r
ggplot(data = titanic,
       aes(x = fare)) +
  geom_histogram(binwidth = 15, 
*                fill = "darkred")
```

---

```r
ggplot(data = titanic,
       aes(x = fare)) +
  geom_histogram(binwidth = 15, 
*                color = "white",
*                fill = "darkred")
```

---

---

## Stacked Bar-Plot

```r
ggplot(data = titanic,
       aes(x = pclass, 
*          fill = survived)) +
  geom_bar() 
```
]

![](03b-intro-ggplot_files/figure-html/unnamed-chunk-29-1.png)
]

---

## Standardized Bar Plot

```r
ggplot(data = titanic,
       aes(x = pclass, 
           fill = survived)) + 
* geom_bar(position = "fill")
```
]

![](03b-intro-ggplot_files/figure-html/unnamed-chunk-31-1.png)
]

---

## Dodged Bar Plot

```r
ggplot(data = titanic,
       aes(x = pclass, 
           fill = survived)) + 
* geom_bar(position = "dodge")
```
]

![](03b-intro-ggplot_files/figure-html/unnamed-chunk-33-1.png)
]

---

## New Data

---

## New Data

```r
glimpse(penguins)
```

```
## Rows: 344
## Columns: 8
## $ species           <fct> Adelie, Adelie, Adelie, Adelie, Adelie, Adelie, Ade…
## $ island            <fct> Torgersen, Torgersen, Torgersen, Torgersen, Torgers…
## $ bill_length_mm    <dbl> 39.1, 39.5, 40.3, NA, 36.7, 39.3, 38.9, 39.2, 34.1,…
## $ bill_depth_mm     <dbl> 18.7, 17.4, 18.0, NA, 19.3, 20.6, 17.8, 19.6, 18.1,…
## $ flipper_length_mm <int> 181, 186, 195, NA, 193, 190, 181, 195, 193, 190, 18…
## $ body_mass_g       <int> 3750, 3800, 3250, NA, 3450, 3650, 3625, 4675, 3475,…
## $ sex               <fct> male, female, female, NA, female, male, female, mal…
## $ year              <int> 2007, 2007, 2007, 2007, 2007, 2007, 2007, 2007, 200…
```

---

---
class: middle inverse

---

```
## Warning: Removed 2 rows containing non-finite values (stat_ydensity).
```

]

- Create a ggplot using the `penguins` data frame.
- Map the `species` to the x-axis and `bill_length_mm` to the y-axis. 
- Add a layer of a violin plot.

]

```r
ggplot(penguins,
       aes(x = species,
           y = bill_length_mm))  +
  geom_violin()
```

]

---

]

---
class: inverse middle

---

```r
ggplot(penguins,
       aes(x = bill_depth_mm,
           y = bill_length_mm))  +
  geom_point()
```

]

```
## Warning: Removed 2 rows containing missing values (geom_point).
```

![](03b-intro-ggplot_files/figure-html/unnamed-chunk-42-1.png)

]

---

---

```r
ggplot(penguins,
       aes(x = bill_depth_mm,
           y = bill_length_mm,
           color = species)) +
  geom_point()
```

]

```
## Warning: Removed 2 rows containing missing values (geom_point).
```

![](03b-intro-ggplot_files/figure-html/unnamed-chunk-44-1.png)

]

---
.left-panel[

```r
ggplot(penguins,
       aes(x = bill_depth_mm,
           y = bill_length_mm,
           shape = species)) +
  geom_point()
```

]

```
## Warning: Removed 2 rows containing missing values (geom_point).
```

![](03b-intro-ggplot_files/figure-html/unnamed-chunk-46-1.png)

]

---

```r
ggplot(penguins,
       aes(x = bill_depth_mm,
           y = bill_length_mm,
           shape = species)) +
  geom_point()
```

]

```
## Warning: Removed 2 rows containing missing values (geom_point).
```

![](03b-intro-ggplot_files/figure-html/unnamed-chunk-48-1.png)

]

---

```r
ggplot(penguins,
       aes(x = bill_depth_mm,
           y = bill_length_mm,
           shape = species,
           color = species)) +
  geom_point()
```

]

```
## Warning: Removed 2 rows containing missing values (geom_point).
```

![](03b-intro-ggplot_files/figure-html/unnamed-chunk-50-1.png)

]

---

```r
ggplot(penguins,
       aes(x = bill_depth_mm,
           y = bill_length_mm,
           shape = species,
           color = species,
           size = body_mass_g)) +
  geom_point()
```

]

```
## Warning: Removed 2 rows containing missing values (geom_point).
```

![](03b-intro-ggplot_files/figure-html/unnamed-chunk-52-1.png)
]

---