Data Joins

<br>
<br>
.right-panel[

# Data Joins
## Dr. Mine Dogucu
]

---
class: middle

.font15[Image from [R for Data Science book](https://r4ds.had.co.nz/index.html) licensed under the [Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License](https://creativecommons.org/licenses/by-nc-nd/3.0/us/)]

---

## Inner Join

---

#### Outer Joins

---

## Data Joins

---

```r
artists
```

```
## # A tibble: 4 x 2
##   name          followers
##   <chr>             <dbl>
## 1 Beyoncé        24757958
## 2 Taylor Swift   33098116
## 3 Ariana Grande  51807131
## 4 Drake          50252529
```

]

```r
songs
```

```
## # A tibble: 5 x 4
##   name       song_name                 album_name                song_popularity
##   <chr>      <chr>                     <chr>                               <dbl>
## 1 Beyoncé    Savage Remix (feat. Beyo… Savage Remix (feat. Beyo…              83
## 2 Taylor Sw… cardigan                  folklore                               85
## 3 Drake      Laugh Now Cry Later (fea… Laugh Now Cry Later (fea…              95
## 4 Beyoncé    Halo                      I AM…SASHA FIERCE                      NA
## 5 Ariana Gr… Stuck with U (with Justi… Stuck with U                           NA
```

]

```r
albums
```

```
## # A tibble: 4 x 2
##   album_name                           album_release_date
##   <chr>                                <date>            
## 1 Savage Remix (feat. Beyoncé)         2020-04-29        
## 2 I AM…SASHA FIERCE                    2008-11-14        
## 3 Stuck with U                         2020-05-08        
## 4 Laugh Now Cry Later (feat. Lil Durk) 2020-08-14
```

]
]

---

---

## Join Functions

`something_join(x, y)` All the join functions in dplyr package are in this fashion where x represents the first data frame and y represents the second data frame.

---

```r
songs
```

]

```r
albums
```

]

```r
left_join(songs, albums, by = "album_name")
```

```
## # A tibble: 5 x 5
##   name     song_name          album_name        song_popularity album_release_d…
##   <chr>    <chr>              <chr>                       <dbl> <date>          
## 1 Beyoncé  Savage Remix (fea… Savage Remix (fe…              83 2020-04-29      
## 2 Taylor … cardigan           folklore                       85 NA              
## 3 Drake    Laugh Now Cry Lat… Laugh Now Cry La…              95 2020-08-14      
## 4 Beyoncé  Halo               I AM…SASHA FIERCE              NA 2008-11-14      
## 5 Ariana … Stuck with U (wit… Stuck with U                   NA 2020-05-08
```

]

`left_join()` includes all rows from x

---

```r
songs
```

]

```r
albums
```

]

```r
right_join(songs, albums, by = "album_name")
```

```
## # A tibble: 4 x 5
##   name     song_name          album_name        song_popularity album_release_d…
##   <chr>    <chr>              <chr>                       <dbl> <date>          
## 1 Beyoncé  Savage Remix (fea… Savage Remix (fe…              83 2020-04-29      
## 2 Drake    Laugh Now Cry Lat… Laugh Now Cry La…              95 2020-08-14      
## 3 Beyoncé  Halo               I AM…SASHA FIERCE              NA 2008-11-14      
## 4 Ariana … Stuck with U (wit… Stuck with U                   NA 2020-05-08
```

]

`right_join()` includes all rows from `y`

---

```r
songs
```

]

```r
albums
```

]

```r
inner_join(songs, albums, by = "album_name")
```

]

`inner_join()` includes all rows that are in x **and** y

---

```r
songs
```

]

```r
albums
```

]

```r
full_join(songs, albums, by = "album_name")
```

]

`full_join()` includes all rows that are in x **or** y

---

```r
artists
```

]

```r
songs
```

]

```r
albums
```

]

```r
full_join(artists, songs, by = "name") %>% 
  full_join(albums, by = "album_name")
```

```
## # A tibble: 5 x 6
##   name    followers song_name     album_name    song_popularity album_release_d…
##   <chr>       <dbl> <chr>         <chr>                   <dbl> <date>          
## 1 Beyoncé  24757958 Savage Remix… Savage Remix…              83 2020-04-29      
## 2 Beyoncé  24757958 Halo          I AM…SASHA F…              NA 2008-11-14      
## 3 Taylor…  33098116 cardigan      folklore                   85 NA              
## 4 Ariana…  51807131 Stuck with U… Stuck with U               NA 2020-05-08      
## 5 Drake    50252529 Laugh Now Cr… Laugh Now Cr…              95 2020-08-14
```

]