String Manipulation

class: center, middle

### String Manipulation with `stringr`

### Kelly McConville

.large[Math 241 | Week 9 | Spring 2021]

---

## Announcements/Reminders

* Mini Project 2 is due Thursday.
    + Will start grading at noon on Sunday.

---

## And here we are!

**String**

```r
x <- "cat"
```

**Character vector**

```r
x <- c("dog", "cat", "mouse")
```

**Factor vector**

```r
x <- factor(x)
levels(x)
```

```
## [1] "cat"   "dog"   "mouse"
```
    
---
  
## Goals for Today: [Stringr](https://cran.r-project.org/web/packages/stringr/vignettes/stringr.html)

* Learn how to handle character vectors!
    + Character manipulation
    + Pattern matching

* Let's look at some of the functionalities of `stringr` using a character vector of song lyrics.

```r
library(stringr)
```

---

## Our Toy Lyric

* Song?
* Artist?

```r
lyric <- c("But I would walk 500 miles,",
 "And I would walk 500 more,",
 "Just to be the man who walks a 1000 miles,",
 "To fall down at your door")
lyric
```

```
## [1] "But I would walk 500 miles,"               
## [2] "And I would walk 500 more,"                
## [3] "Just to be the man who walks a 1000 miles,"
## [4] "To fall down at your door"
```

---

## String Length

```r
length(lyric)
```

```
## [1] 4
```

```r
str_length(lyric)
```

```
## [1] 27 26 42 25
```

---

## Accessing and Replacing

```r
str_sub(string = lyric[1], start = 18, end = 20)
```

```
## [1] "500"
```

```r
str_sub(string = lyric[1], start = 18, end = 20) <- "2"
```

```r
lyric
```

```
## [1] "But I would walk 2 miles,"                 
## [2] "And I would walk 500 more,"                
## [3] "Just to be the man who walks a 1000 miles,"
## [4] "To fall down at your door"
```

---

## Change Cases

```r
str_to_upper(lyric)
```

```
## [1] "BUT I WOULD WALK 2 MILES,"                 
## [2] "AND I WOULD WALK 500 MORE,"                
## [3] "JUST TO BE THE MAN WHO WALKS A 1000 MILES,"
## [4] "TO FALL DOWN AT YOUR DOOR"
```

```r
str_to_title(lyric)
```

```
## [1] "But I Would Walk 2 Miles,"                 
## [2] "And I Would Walk 500 More,"                
## [3] "Just To Be The Man Who Walks A 1000 Miles,"
## [4] "To Fall Down At Your Door"
```

```r
str_to_lower(lyric)
```

```
## [1] "but i would walk 2 miles,"                 
## [2] "and i would walk 500 more,"                
## [3] "just to be the man who walks a 1000 miles,"
## [4] "to fall down at your door"
```

---

## Sorting

```r
str_sort(lyric)
```

```
## [1] "And I would walk 500 more,"                
## [2] "But I would walk 2 miles,"                 
## [3] "Just to be the man who walks a 1000 miles,"
## [4] "To fall down at your door"
```

---

## Pattern Matching

* Learn to:
    + Detect [pattern]()
    + Extract [pattern]()
    + Replace [pattern]()
    + Split [pattern]()

* Look at the [`stringr` cheatsheet](https://github.com/rstudio/cheatsheets/raw/master/strings.pdf).

---

## Common Goal: Match a particular pattern

* I want to match the pattern `500` from `lyric`.

```r
lyric
```

```
## [1] "But I would walk 2 miles,"                 
## [2] "And I would walk 500 more,"                
## [3] "Just to be the man who walks a 1000 miles,"
## [4] "To fall down at your door"
```

```r
str_view_all(string = lyric, pattern = "500")
```

<div id="htmlwidget-2d367967fdf73c536a03" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-2d367967fdf73c536a03">{"x":{"html":"<ul>\n <li>But I would walk 2 miles,<\/li>\n <li>And I would walk 500<\/span> more,<\/li>\n <li>Just to be the man who walks a 1000 miles,<\/li>\n <li>To fall down at your door<\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

## Let's make it more general.

* I want to locate all the numbers.

```r
lyric
```

```
## [1] "But I would walk 2 miles,"                 
## [2] "And I would walk 500 more,"                
## [3] "Just to be the man who walks a 1000 miles,"
## [4] "To fall down at your door"
```

```r
str_view_all(lyric, "500|1000|2")
```

<div id="htmlwidget-f32eef1aba47abbb0609" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-f32eef1aba47abbb0609">{"x":{"html":"<ul>\n <li>But I would walk 2<\/span> miles,<\/li>\n <li>And I would walk 500<\/span> more,<\/li>\n <li>Just to be the man who walks a 1000<\/span> miles,<\/li>\n <li>To fall down at your door<\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

How should we modify the code to locate all the numbers from these lyrics of various songs?

```r
lyrics <- c("But I would walk 500 miles",
 "2000 0 0 party over oops out of time!", 
 "1 is the loneliest number that you'll ever do",
 "When I'm 64",
 "Where 2 and 2 always makes a 5",
 "1, 2, 3, 4: Tell me that you love me more")
```

```r
str_view_all(lyrics, "500|1000|2")
```

<div id="htmlwidget-36d7ddef8ee161eab931" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-36d7ddef8ee161eab931">{"x":{"html":"<ul>\n <li>But I would walk 500<\/span> miles<\/li>\n <li>2<\/span>000 0 0 party over oops out of time!<\/li>\n <li>1 is the loneliest number that you'll ever do<\/li>\n <li>When I'm 64<\/li>\n <li>Where 2<\/span> and 2<\/span> always makes a 5<\/li>\n <li>1, 2<\/span>, 3, 4: Tell me that you love me more<\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

How should we modify the code to locate all the numbers from these lyrics of various songs?

```r
str_view_all(lyrics, "500|1000|0|2000|1|64|2|5|3|4")
```

<div id="htmlwidget-9e3089b0bd50048fccf2" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-9e3089b0bd50048fccf2">{"x":{"html":"<ul>\n <li>But I would walk 500<\/span> miles<\/li>\n <li>2000<\/span> 0<\/span> 0<\/span> party over oops out of time!<\/li>\n <li>1<\/span> is the loneliest number that you'll ever do<\/li>\n <li>When I'm 64<\/span><\/li>\n <li>Where 2<\/span> and 2<\/span> always makes a 5<\/span><\/li>\n <li>1<\/span>, 2<\/span>, 3<\/span>, 4<\/span>: Tell me that you love me more<\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

But now imagine you had a very long vector and you want to locate any number?

```r
str_view_all(lyrics, "1|2|3|4...")
```

Not a good approach!

---

## Regular Expressions

* A concise language for describing patterns in strings.
    + But not super easy to read.
    + Good to have cheatsheets and the internet for help!

* Neat RStudio Addin to help: [`RegExplain`](https://www.garrickadenbuie.com/project/regexplain/)

---

## Regular Expressions

* `[:digit:]` is a particular [Character Class](https://stat.ethz.ch/R-manual/R-devel/library/base/html/regex.html)
* Character classes are a way of specifying that you want to match one of the following characters.

```r
str_view_all(lyrics, "[:digit:]")
```

<div id="htmlwidget-3c2a26d281286d110eec" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-3c2a26d281286d110eec">{"x":{"html":"<ul>\n <li>But I would walk 5<\/span>0<\/span>0<\/span> miles<\/li>\n <li>2<\/span>0<\/span>0<\/span>0<\/span> 0<\/span> 0<\/span> party over oops out of time!<\/li>\n <li>1<\/span> is the loneliest number that you'll ever do<\/li>\n <li>When I'm 6<\/span>4<\/span><\/li>\n <li>Where 2<\/span> and 2<\/span> always makes a 5<\/span><\/li>\n <li>1<\/span>, 2<\/span>, 3<\/span>, 4<\/span>: Tell me that you love me more<\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

## Regular Expressions

* `+` is a quantifier
    * `+`: One or more

```r
str_view_all(lyrics, "[:digit:]+")
```

<div id="htmlwidget-d2ad81a720a849d97990" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-d2ad81a720a849d97990">{"x":{"html":"<ul>\n <li>But I would walk 500<\/span> miles<\/li>\n <li>2000<\/span> 0<\/span> 0<\/span> party over oops out of time!<\/li>\n <li>1<\/span> is the loneliest number that you'll ever do<\/li>\n <li>When I'm 64<\/span><\/li>\n <li>Where 2<\/span> and 2<\/span> always makes a 5<\/span><\/li>\n <li>1<\/span>, 2<\/span>, 3<\/span>, 4<\/span>: Tell me that you love me more<\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

## Regular Expressions

What does `{n}` do?

```r
str_view_all(lyrics, "[:digit:]{2}")
```

<div id="htmlwidget-c93a2e4050cd0826185e" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-c93a2e4050cd0826185e">{"x":{"html":"<ul>\n <li>But I would walk 50<\/span>0 miles<\/li>\n <li>20<\/span>00<\/span> 0 0 party over oops out of time!<\/li>\n <li>1 is the loneliest number that you'll ever do<\/li>\n <li>When I'm 64<\/span><\/li>\n <li>Where 2 and 2 always makes a 5<\/li>\n <li>1, 2, 3, 4: Tell me that you love me more<\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

## Quantifiers

* `?`: 0 or 1 
* `*`: 0 or more
* `+`: 1 or more
* `{n}`: Exactly n
* `{n,}`: n or more
* `{,m}`: at most m
* `{n,m}`: between n and m

---

## Character Classes

* What pattern does this regexp match?

```r
str_view_all(lyrics, "[:alpha:]")
```

<div id="htmlwidget-6e41058cca4e9067527a" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-6e41058cca4e9067527a">{"x":{"html":"<ul>\n <li>B<\/span>u<\/span>t<\/span> I<\/span> w<\/span>o<\/span>u<\/span>l<\/span>d<\/span> w<\/span>a<\/span>l<\/span>k<\/span> 500 m<\/span>i<\/span>l<\/span>e<\/span>s<\/span><\/li>\n <li>2000 0 0 p<\/span>a<\/span>r<\/span>t<\/span>y<\/span> o<\/span>v<\/span>e<\/span>r<\/span> o<\/span>o<\/span>p<\/span>s<\/span> o<\/span>u<\/span>t<\/span> o<\/span>f<\/span> t<\/span>i<\/span>m<\/span>e<\/span>!<\/li>\n <li>1 i<\/span>s<\/span> t<\/span>h<\/span>e<\/span> l<\/span>o<\/span>n<\/span>e<\/span>l<\/span>i<\/span>e<\/span>s<\/span>t<\/span> n<\/span>u<\/span>m<\/span>b<\/span>e<\/span>r<\/span> t<\/span>h<\/span>a<\/span>t<\/span> y<\/span>o<\/span>u<\/span>'l<\/span>l<\/span> e<\/span>v<\/span>e<\/span>r<\/span> d<\/span>o<\/span><\/li>\n <li>W<\/span>h<\/span>e<\/span>n<\/span> I<\/span>'m<\/span> 64<\/li>\n <li>W<\/span>h<\/span>e<\/span>r<\/span>e<\/span> 2 a<\/span>n<\/span>d<\/span> 2 a<\/span>l<\/span>w<\/span>a<\/span>y<\/span>s<\/span> m<\/span>a<\/span>k<\/span>e<\/span>s<\/span> a<\/span> 5<\/li>\n <li>1, 2, 3, 4: T<\/span>e<\/span>l<\/span>l<\/span> m<\/span>e<\/span> t<\/span>h<\/span>a<\/span>t<\/span> y<\/span>o<\/span>u<\/span> l<\/span>o<\/span>v<\/span>e<\/span> m<\/span>e<\/span> m<\/span>o<\/span>r<\/span>e<\/span><\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

## Character Classes

* What pattern does this regexp match?

```r
str_view_all(lyrics, "[:upper:]")
```

<div id="htmlwidget-e9760b6704cb5c205bc4" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-e9760b6704cb5c205bc4">{"x":{"html":"<ul>\n <li>B<\/span>ut I<\/span> would walk 500 miles<\/li>\n <li>2000 0 0 party over oops out of time!<\/li>\n <li>1 is the loneliest number that you'll ever do<\/li>\n <li>W<\/span>hen I<\/span>'m 64<\/li>\n <li>W<\/span>here 2 and 2 always makes a 5<\/li>\n <li>1, 2, 3, 4: T<\/span>ell me that you love me more<\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

## Character Classes

* What pattern does this regexp match?

```r
str_view_all(lyrics, "[:alnum:]")
```

<div id="htmlwidget-478a75e1c55871e182a1" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-478a75e1c55871e182a1">{"x":{"html":"<ul>\n <li>B<\/span>u<\/span>t<\/span> I<\/span> w<\/span>o<\/span>u<\/span>l<\/span>d<\/span> w<\/span>a<\/span>l<\/span>k<\/span> 5<\/span>0<\/span>0<\/span> m<\/span>i<\/span>l<\/span>e<\/span>s<\/span><\/li>\n <li>2<\/span>0<\/span>0<\/span>0<\/span> 0<\/span> 0<\/span> p<\/span>a<\/span>r<\/span>t<\/span>y<\/span> o<\/span>v<\/span>e<\/span>r<\/span> o<\/span>o<\/span>p<\/span>s<\/span> o<\/span>u<\/span>t<\/span> o<\/span>f<\/span> t<\/span>i<\/span>m<\/span>e<\/span>!<\/li>\n <li>1<\/span> i<\/span>s<\/span> t<\/span>h<\/span>e<\/span> l<\/span>o<\/span>n<\/span>e<\/span>l<\/span>i<\/span>e<\/span>s<\/span>t<\/span> n<\/span>u<\/span>m<\/span>b<\/span>e<\/span>r<\/span> t<\/span>h<\/span>a<\/span>t<\/span> y<\/span>o<\/span>u<\/span>'l<\/span>l<\/span> e<\/span>v<\/span>e<\/span>r<\/span> d<\/span>o<\/span><\/li>\n <li>W<\/span>h<\/span>e<\/span>n<\/span> I<\/span>'m<\/span> 6<\/span>4<\/span><\/li>\n <li>W<\/span>h<\/span>e<\/span>r<\/span>e<\/span> 2<\/span> a<\/span>n<\/span>d<\/span> 2<\/span> a<\/span>l<\/span>w<\/span>a<\/span>y<\/span>s<\/span> m<\/span>a<\/span>k<\/span>e<\/span>s<\/span> a<\/span> 5<\/span><\/li>\n <li>1<\/span>, 2<\/span>, 3<\/span>, 4<\/span>: T<\/span>e<\/span>l<\/span>l<\/span> m<\/span>e<\/span> t<\/span>h<\/span>a<\/span>t<\/span> y<\/span>o<\/span>u<\/span> l<\/span>o<\/span>v<\/span>e<\/span> m<\/span>e<\/span> m<\/span>o<\/span>r<\/span>e<\/span><\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

## Character Classes

* What pattern does this regexp match?

```r
str_view_all(lyrics, "[:punct:]")
```

<div id="htmlwidget-8c68bc79f2ee9f97d351" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-8c68bc79f2ee9f97d351">{"x":{"html":"<ul>\n <li>But I would walk 500 miles<\/li>\n <li>2000 0 0 party over oops out of time!<\/span><\/li>\n <li>1 is the loneliest number that you'<\/span>ll ever do<\/li>\n <li>When I'<\/span>m 64<\/li>\n <li>Where 2 and 2 always makes a 5<\/li>\n <li>1,<\/span> 2,<\/span> 3,<\/span> 4:<\/span> Tell me that you love me more<\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

## Character Classes

* What pattern does this regexp match?

```r
str_view_all(lyrics, "[:graph:]")
```

<div id="htmlwidget-cdd3d401b5b7671b5f78" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-cdd3d401b5b7671b5f78">{"x":{"html":"<ul>\n <li>B<\/span>u<\/span>t<\/span> I<\/span> w<\/span>o<\/span>u<\/span>l<\/span>d<\/span> w<\/span>a<\/span>l<\/span>k<\/span> 5<\/span>0<\/span>0<\/span> m<\/span>i<\/span>l<\/span>e<\/span>s<\/span><\/li>\n <li>2<\/span>0<\/span>0<\/span>0<\/span> 0<\/span> 0<\/span> p<\/span>a<\/span>r<\/span>t<\/span>y<\/span> o<\/span>v<\/span>e<\/span>r<\/span> o<\/span>o<\/span>p<\/span>s<\/span> o<\/span>u<\/span>t<\/span> o<\/span>f<\/span> t<\/span>i<\/span>m<\/span>e<\/span>!<\/span><\/li>\n <li>1<\/span> i<\/span>s<\/span> t<\/span>h<\/span>e<\/span> l<\/span>o<\/span>n<\/span>e<\/span>l<\/span>i<\/span>e<\/span>s<\/span>t<\/span> n<\/span>u<\/span>m<\/span>b<\/span>e<\/span>r<\/span> t<\/span>h<\/span>a<\/span>t<\/span> y<\/span>o<\/span>u<\/span>'<\/span>l<\/span>l<\/span> e<\/span>v<\/span>e<\/span>r<\/span> d<\/span>o<\/span><\/li>\n <li>W<\/span>h<\/span>e<\/span>n<\/span> I<\/span>'<\/span>m<\/span> 6<\/span>4<\/span><\/li>\n <li>W<\/span>h<\/span>e<\/span>r<\/span>e<\/span> 2<\/span> a<\/span>n<\/span>d<\/span> 2<\/span> a<\/span>l<\/span>w<\/span>a<\/span>y<\/span>s<\/span> m<\/span>a<\/span>k<\/span>e<\/span>s<\/span> a<\/span> 5<\/span><\/li>\n <li>1<\/span>,<\/span> 2<\/span>,<\/span> 3<\/span>,<\/span> 4<\/span>:<\/span> T<\/span>e<\/span>l<\/span>l<\/span> m<\/span>e<\/span> t<\/span>h<\/span>a<\/span>t<\/span> y<\/span>o<\/span>u<\/span> l<\/span>o<\/span>v<\/span>e<\/span> m<\/span>e<\/span> m<\/span>o<\/span>r<\/span>e<\/span><\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

## Character Classes

* What pattern does this regexp match?

```r
str_view_all(lyrics, "[:space:]")
```

<div id="htmlwidget-bad3486fc28b4db2ffe6" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-bad3486fc28b4db2ffe6">{"x":{"html":"<ul>\n <li>But <\/span>I <\/span>would <\/span>walk <\/span>500 <\/span>miles<\/li>\n <li>2000 <\/span>0 <\/span>0 <\/span>party <\/span>over <\/span>oops <\/span>out <\/span>of <\/span>time!<\/li>\n <li>1 <\/span>is <\/span>the <\/span>loneliest <\/span>number <\/span>that <\/span>you'll <\/span>ever <\/span>do<\/li>\n <li>When <\/span>I'm <\/span>64<\/li>\n <li>Where <\/span>2 <\/span>and <\/span>2 <\/span>always <\/span>makes <\/span>a <\/span>5<\/li>\n <li>1, <\/span>2, <\/span>3, <\/span>4: <\/span>Tell <\/span>me <\/span>that <\/span>you <\/span>love <\/span>me <\/span>more<\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

## Character Classes

* Can also create your own.

* What pattern does this regexp match?

```r
str_view_all(lyrics, "[aeiou]")
```

<div id="htmlwidget-273b0681db2304d2f1d3" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-273b0681db2304d2f1d3">{"x":{"html":"<ul>\n <li>Bu<\/span>t I wo<\/span>u<\/span>ld wa<\/span>lk 500 mi<\/span>le<\/span>s<\/li>\n <li>2000 0 0 pa<\/span>rty o<\/span>ve<\/span>r o<\/span>o<\/span>ps o<\/span>u<\/span>t o<\/span>f ti<\/span>me<\/span>!<\/li>\n <li>1 i<\/span>s the<\/span> lo<\/span>ne<\/span>li<\/span>e<\/span>st nu<\/span>mbe<\/span>r tha<\/span>t yo<\/span>u<\/span>'ll e<\/span>ve<\/span>r do<\/span><\/li>\n <li>Whe<\/span>n I'm 64<\/li>\n <li>Whe<\/span>re<\/span> 2 a<\/span>nd 2 a<\/span>lwa<\/span>ys ma<\/span>ke<\/span>s a<\/span> 5<\/li>\n <li>1, 2, 3, 4: Te<\/span>ll me<\/span> tha<\/span>t yo<\/span>u<\/span> lo<\/span>ve<\/span> me<\/span> mo<\/span>re<\/span><\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

## Other Handy Regexps

* What pattern does this regexp match?

* Why do we need an extra `\`?

```r
str_view_all(lyrics, "\\d")
```

<div id="htmlwidget-e3e0f72fcbc979625d60" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-e3e0f72fcbc979625d60">{"x":{"html":"<ul>\n <li>But I would walk 5<\/span>0<\/span>0<\/span> miles<\/li>\n <li>2<\/span>0<\/span>0<\/span>0<\/span> 0<\/span> 0<\/span> party over oops out of time!<\/li>\n <li>1<\/span> is the loneliest number that you'll ever do<\/li>\n <li>When I'm 6<\/span>4<\/span><\/li>\n <li>Where 2<\/span> and 2<\/span> always makes a 5<\/span><\/li>\n <li>1<\/span>, 2<\/span>, 3<\/span>, 4<\/span>: Tell me that you love me more<\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

## Espacing Meta Characters

* `\` is a special character that has a particular meaning in `r`.

* You can see all the special characters that need escaping in the help page for `'`:

```r
?"'"
```

---

## Other Handy Regexps

* What pattern does this regexp match?

```r
str_view_all(lyrics, ".w.")
```

<div id="htmlwidget-6b8cebf74187c00c7ab3" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-6b8cebf74187c00c7ab3">{"x":{"html":"<ul>\n <li>But I wo<\/span>uld wa<\/span>lk 500 miles<\/li>\n <li>2000 0 0 party over oops out of time!<\/li>\n <li>1 is the loneliest number that you'll ever do<\/li>\n <li>When I'm 64<\/li>\n <li>Where 2 and 2 alwa<\/span>ys makes a 5<\/li>\n <li>1, 2, 3, 4: Tell me that you love me more<\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

## Other Handy Regexps

* What pattern does this regexp match?

```r
str_view_all(lyrics, "\\W")
```

<div id="htmlwidget-30c9d30cad066081c54e" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-30c9d30cad066081c54e">{"x":{"html":"<ul>\n <li>But <\/span>I <\/span>would <\/span>walk <\/span>500 <\/span>miles<\/li>\n <li>2000 <\/span>0 <\/span>0 <\/span>party <\/span>over <\/span>oops <\/span>out <\/span>of <\/span>time!<\/span><\/li>\n <li>1 <\/span>is <\/span>the <\/span>loneliest <\/span>number <\/span>that <\/span>you'<\/span>ll <\/span>ever <\/span>do<\/li>\n <li>When <\/span>I'<\/span>m <\/span>64<\/li>\n <li>Where <\/span>2 <\/span>and <\/span>2 <\/span>always <\/span>makes <\/span>a <\/span>5<\/li>\n <li>1,<\/span> <\/span>2,<\/span> <\/span>3,<\/span> <\/span>4:<\/span> <\/span>Tell <\/span>me <\/span>that <\/span>you <\/span>love <\/span>me <\/span>more<\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

## Other Handy Regexps

* What pattern does this regexp match?

```r
str_view_all(lyrics, "Whe(n|re)")
```

<div id="htmlwidget-ea0f530accca96a388f0" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-ea0f530accca96a388f0">{"x":{"html":"<ul>\n <li>But I would walk 500 miles<\/li>\n <li>2000 0 0 party over oops out of time!<\/li>\n <li>1 is the loneliest number that you'll ever do<\/li>\n <li>When<\/span> I'm 64<\/li>\n <li>Where<\/span> 2 and 2 always makes a 5<\/li>\n <li>1, 2, 3, 4: Tell me that you love me more<\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

## Groups

* What pattern does this regexp match?

```r
str_view_all(lyrics, "(\\d)\\1")
```

<div id="htmlwidget-cc1a460ad243b3edb4b6" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-cc1a460ad243b3edb4b6">{"x":{"html":"<ul>\n <li>But I would walk 500<\/span> miles<\/li>\n <li>200<\/span>0 0 0 party over oops out of time!<\/li>\n <li>1 is the loneliest number that you'll ever do<\/li>\n <li>When I'm 64<\/li>\n <li>Where 2 and 2 always makes a 5<\/li>\n <li>1, 2, 3, 4: Tell me that you love me more<\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

## Groups

* What pattern does this regexp match?

```r
str_view_all(lyrics, "(\\d)\\1\\1")
```

<div id="htmlwidget-a7fe429c68253b31d7ef" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-a7fe429c68253b31d7ef">{"x":{"html":"<ul>\n <li>But I would walk 500 miles<\/li>\n <li>2000<\/span> 0 0 party over oops out of time!<\/li>\n <li>1 is the loneliest number that you'll ever do<\/li>\n <li>When I'm 64<\/li>\n <li>Where 2 and 2 always makes a 5<\/li>\n <li>1, 2, 3, 4: Tell me that you love me more<\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

## Groups

* What pattern does this regexp match?

```r
str_view_all(lyrics, "([:alnum:])(\\s)[:alnum:]+\\2\\1")
```

<div id="htmlwidget-c5097cd7f106f511fd9a" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-c5097cd7f106f511fd9a">{"x":{"html":"<ul>\n <li>But I would walk 500 miles<\/li>\n <li>2000 0 0<\/span> party over oops out of t<\/span>ime!<\/li>\n <li>1 is the loneliest number t<\/span>hat you'll ever do<\/li>\n <li>When I'm 64<\/li>\n <li>Where 2 and 2<\/span> always makes a 5<\/li>\n <li>1, 2, 3, 4: Tell me that you love me more<\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

## Other Handy Regexps

* What pattern does this regexp match?

```r
str_view_all(lyrics, "\\b")
```

<div id="htmlwidget-f4e33f96af67aa153af0" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-f4e33f96af67aa153af0">{"x":{"html":"<ul>\n <li><\/span>But<\/span> <\/span>I<\/span> <\/span>would<\/span> <\/span>walk<\/span> <\/span>500<\/span> <\/span>miles<\/span><\/li>\n <li><\/span>2000<\/span> <\/span>0<\/span> <\/span>0<\/span> <\/span>party<\/span> <\/span>over<\/span> <\/span>oops<\/span> <\/span>out<\/span> <\/span>of<\/span> <\/span>time<\/span>!<\/li>\n <li><\/span>1<\/span> <\/span>is<\/span> <\/span>the<\/span> <\/span>loneliest<\/span> <\/span>number<\/span> <\/span>that<\/span> <\/span>you<\/span>'<\/span>ll<\/span> <\/span>ever<\/span> <\/span>do<\/span><\/li>\n <li><\/span>When<\/span> <\/span>I<\/span>'<\/span>m<\/span> <\/span>64<\/span><\/li>\n <li><\/span>Where<\/span> <\/span>2<\/span> <\/span>and<\/span> <\/span>2<\/span> <\/span>always<\/span> <\/span>makes<\/span> <\/span>a<\/span> <\/span>5<\/span><\/li>\n <li><\/span>1<\/span>, <\/span>2<\/span>, <\/span>3<\/span>, <\/span>4<\/span>: <\/span>Tell<\/span> <\/span>me<\/span> <\/span>that<\/span> <\/span>you<\/span> <\/span>love<\/span> <\/span>me<\/span> <\/span>more<\/span><\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

## Anchors

* What pattern does this regexp match?

```r
str_view_all(lyrics, "^\\d+")
```

<div id="htmlwidget-9dc34cc1fdd10007963d" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-9dc34cc1fdd10007963d">{"x":{"html":"<ul>\n <li>But I would walk 500 miles<\/li>\n <li>2000<\/span> 0 0 party over oops out of time!<\/li>\n <li>1<\/span> is the loneliest number that you'll ever do<\/li>\n <li>When I'm 64<\/li>\n <li>Where 2 and 2 always makes a 5<\/li>\n <li>1<\/span>, 2, 3, 4: Tell me that you love me more<\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

## Anchors

* What pattern does this regexp match?

```r
str_view_all(lyrics, "\\d+$")
```

<div id="htmlwidget-77bf4d240ee797187220" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-77bf4d240ee797187220">{"x":{"html":"<ul>\n <li>But I would walk 500 miles<\/li>\n <li>2000 0 0 party over oops out of time!<\/li>\n <li>1 is the loneliest number that you'll ever do<\/li>\n <li>When I'm 64<\/span><\/li>\n <li>Where 2 and 2 always makes a 5<\/span><\/li>\n <li>1, 2, 3, 4: Tell me that you love me more<\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

## Alternates

* What pattern does this regexp match?

```r
str_view_all(lyrics, "[^aeiou]")
```

<div id="htmlwidget-557108fb0feb10e05686" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-557108fb0feb10e05686">{"x":{"html":"<ul>\n <li>B<\/span>ut<\/span> <\/span>I<\/span> <\/span>w<\/span>oul<\/span>d<\/span> <\/span>w<\/span>al<\/span>k<\/span> <\/span>5<\/span>0<\/span>0<\/span> <\/span>m<\/span>il<\/span>es<\/span><\/li>\n <li>2<\/span>0<\/span>0<\/span>0<\/span> <\/span>0<\/span> <\/span>0<\/span> <\/span>p<\/span>ar<\/span>t<\/span>y<\/span> <\/span>ov<\/span>er<\/span> <\/span>oop<\/span>s<\/span> <\/span>out<\/span> <\/span>of<\/span> <\/span>t<\/span>im<\/span>e!<\/span><\/li>\n <li>1<\/span> <\/span>is<\/span> <\/span>t<\/span>h<\/span>e <\/span>l<\/span>on<\/span>el<\/span>ies<\/span>t<\/span> <\/span>n<\/span>um<\/span>b<\/span>er<\/span> <\/span>t<\/span>h<\/span>at<\/span> <\/span>y<\/span>ou'<\/span>l<\/span>l<\/span> <\/span>ev<\/span>er<\/span> <\/span>d<\/span>o<\/li>\n <li>W<\/span>h<\/span>en<\/span> <\/span>I<\/span>'<\/span>m<\/span> <\/span>6<\/span>4<\/span><\/li>\n <li>W<\/span>h<\/span>er<\/span>e <\/span>2<\/span> <\/span>an<\/span>d<\/span> <\/span>2<\/span> <\/span>al<\/span>w<\/span>ay<\/span>s<\/span> <\/span>m<\/span>ak<\/span>es<\/span> <\/span>a <\/span>5<\/span><\/li>\n <li>1<\/span>,<\/span> <\/span>2<\/span>,<\/span> <\/span>3<\/span>,<\/span> <\/span>4<\/span>:<\/span> <\/span>T<\/span>el<\/span>l<\/span> <\/span>m<\/span>e <\/span>t<\/span>h<\/span>at<\/span> <\/span>y<\/span>ou <\/span>l<\/span>ov<\/span>e <\/span>m<\/span>e <\/span>m<\/span>or<\/span>e<\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

## Alternates

* What pattern does this regexp match?

```r
str_view_all(lyrics, "o[m-z]")
```

<div id="htmlwidget-578f61d87150582283fb" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-578f61d87150582283fb">{"x":{"html":"<ul>\n <li>But I wou<\/span>ld walk 500 miles<\/li>\n <li>2000 0 0 party ov<\/span>er oo<\/span>ps ou<\/span>t of time!<\/li>\n <li>1 is the lon<\/span>eliest number that you<\/span>'ll ever do<\/li>\n <li>When I'm 64<\/li>\n <li>Where 2 and 2 always makes a 5<\/li>\n <li>1, 2, 3, 4: Tell me that you<\/span> lov<\/span>e me mor<\/span>e<\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

## Look Arounds

```r
str_view_all(lyrics, "[:alpha:]+(?= \\d+)")
```

<div id="htmlwidget-61dc26666c1b9a18964e" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-61dc26666c1b9a18964e">{"x":{"html":"<ul>\n <li>But I would walk<\/span> 500 miles<\/li>\n <li>2000 0 0 party over oops out of time!<\/li>\n <li>1 is the loneliest number that you'll ever do<\/li>\n <li>When I'm<\/span> 64<\/li>\n <li>Where<\/span> 2 and<\/span> 2 always makes a<\/span> 5<\/li>\n <li>1, 2, 3, 4: Tell me that you love me more<\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

## Look Arounds

```r
str_view_all(lyrics, "(?<=\\d )[:alpha:]+")
```

<div id="htmlwidget-2d217f1961d143be6889" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-2d217f1961d143be6889">{"x":{"html":"<ul>\n <li>But I would walk 500 miles<\/span><\/li>\n <li>2000 0 0 party<\/span> over oops out of time!<\/li>\n <li>1 is<\/span> the loneliest number that you'll ever do<\/li>\n <li>When I'm 64<\/li>\n <li>Where 2 and<\/span> 2 always<\/span> makes a 5<\/li>\n <li>1, 2, 3, 4: Tell me that you love me more<\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

## Your Turn!

* Work on the `regexp.Rmd`.
    + In the Handouts folder in our shared RStudio folder (`/home/courses/math241s21/Handouts/regexp`).

---

## Pattern Matching

* The `str_view_all()` is a nice helper function.

* Now need to learn functions to take **action** based on our regular expression pattern matching.

* Learn to:
    + Detect [pattern]()
    + Extract [pattern]()
    + Replace [pattern]()
    + Split [pattern]()
    
---

## New Example: Whole Song from [`genuis`](https://github.com/josiahparry/genius)

```r
library(genius)
hey_jude <- genius_lyrics(artist = "The Beatles", 
 song = "Hey Jude")
hey_jude
```

```
## # A tibble: 53 x 3
## track_title line lyric 
## <chr> <int> <chr> 
## 1 Hey Jude 1 Hey Jude, don't make it bad 
## 2 Hey Jude 2 Take a sad song and make it better 
## 3 Hey Jude 3 Remember to let her into your heart 
## 4 Hey Jude 4 Then you can start to make it better 
## 5 Hey Jude 5 Hey Jude, don't be afraid 
## 6 Hey Jude 6 You were made to go out and get her 
## 7 Hey Jude 7 The minute you let her under your skin 
## 8 Hey Jude 8 Then you begin to make it better 
## 9 Hey Jude 9 And anytime you feel the pain, hey Jude, refrain
## 10 Hey Jude 10 Don't carry the world upon your shoulders 
## # … with 43 more rows
```

---

## Detect

```r
str_detect(string = hey_jude$lyric, pattern = "Jude")
```

```
##  [1]  TRUE FALSE FALSE FALSE  TRUE FALSE FALSE FALSE  TRUE FALSE FALSE FALSE
## [13] FALSE  TRUE FALSE FALSE  TRUE FALSE  TRUE FALSE  TRUE FALSE FALSE  TRUE
## [25] FALSE FALSE FALSE FALSE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE
## [37]  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE FALSE  TRUE  TRUE
## [49]  TRUE FALSE  TRUE  TRUE  TRUE
```

---

## Detect

```r
str_subset(string = hey_jude$lyric, pattern = "Jude")
```

```
##  [1] "Hey Jude, don't make it bad"                                                                               
##  [2] "Hey Jude, don't be afraid"                                                                                 
##  [3] "And anytime you feel the pain, hey Jude, refrain"                                                          
##  [4] "Hey Jude, don't let me down"                                                                               
##  [5] "Remember (Hey Jude) to let her into your heart"                                                            
##  [6] "So let it out and let it in, hey Jude, begin"                                                              
##  [7] "And don't you know that it's just you, hey Jude, you'll do"                                                
##  [8] "Hey Jude, don't make it bad"                                                                               
##  [9] "Naa na na na na na na, na na na na, hey Jude"                                                              
## [10] "Naa na na na na na na, na na na na, hey Jude"                                                              
## [11] "Naa na na na na na na, na na na na, hey Jude"                                                              
## [12] "Naa na na na na na na, na na na na, hey Jude"                                                              
## [13] "(Jude Judy Judy Judy Judy Judy owwwww wowww)"                                                              
## [14] "Naa na na na na na na (Na na na), na na na na, hey Jude"                                                   
## [15] "(Jude Jude Jude Jude Jude)"                                                                                
## [16] "Naa na na na na na na (Yeah yeah yeah), na na na na, hey Jude"                                             
## [17] "(You know you can make, Jude Jude, You're not gonna break it)"                                             
## [18] "Naa na (Don't make it bad Jude) na na na na na (Take a sad song and make it better), na na na na, hey Jude"
## [19] "Hey Jude, hey Jude wowwwwww"                                                                               
## [20] "Naa na na na na na na, na na na na, hey Jude"                                                              
## [21] "Naa na na na na na na, na na na na, hey Jude"                                                              
## [22] "Jude Jude Jude Jude Jude Jude"                                                                             
## [23] "Naa na na na na na na, na na na na, hey Jude"                                                              
## [24] "Naa na na na na na na, na na na na, hey Jude"                                                              
## [25] "Naa na na na na na na, na na na na, hey Jude"                                                              
## [26] "Naa na na na na na na, na na na na, hey Jude"                                                              
## [27] "Naa na na na na na na (Make it Jude), na na na na, hey Jude"                                               
## [28] "Naa na na na na na na, na na na na, hey Jude(Go listen to ya ma ma ma ma ma ma ma ma)"                     
## [29] "Naa na na na na na na, na na na na, hey Jude"                                                              
## [30] "Naa na na na na na na, na na na na, hey Jude"
```

---

## Detect

```r
hey_jude %>%
  filter(str_detect(string = lyric, pattern = "Jude"))
```

```
## # A tibble: 30 x 3
## track_title line lyric 
## <chr> <int> <chr> 
## 1 Hey Jude 1 Hey Jude, don't make it bad 
## 2 Hey Jude 5 Hey Jude, don't be afraid 
## 3 Hey Jude 9 And anytime you feel the pain, hey Jude, refrain 
## 4 Hey Jude 14 Hey Jude, don't let me down 
## 5 Hey Jude 17 Remember (Hey Jude) to let her into your heart 
## 6 Hey Jude 19 So let it out and let it in, hey Jude, begin 
## 7 Hey Jude 21 And don't you know that it's just you, hey Jude, you'll do
## 8 Hey Jude 24 Hey Jude, don't make it bad 
## 9 Hey Jude 30 Naa na na na na na na, na na na na, hey Jude 
## 10 Hey Jude 31 Naa na na na na na na, na na na na, hey Jude 
## # … with 20 more rows
```

---

## Detect

```r
str_count(string = hey_jude$lyric, pattern = "(n|N)a+")
```

```
##  [1]  0  0  0  0  0  0  0  0  0  0  0  0 10  0  0  0  0  0  0  0  0  0  9  0  0
## [26]  0  0  0  0 11 11 11 11  0 14  0 11  1 11  0 11 11  0 11 11 12 11 11 11  0
## [51] 11 11 11
```

---

## Detect

```r
hey_jude %>%
  filter(str_count(string = hey_jude$lyric, 
                   pattern = "(n|N)a+") > 0)
```

```
## # A tibble: 21 x 3
## track_title line lyric 
## <chr> <int> <chr> 
## 1 Hey Jude 13 Na na na na na na na na na na 
## 2 Hey Jude 23 Na na na na na na na na na yeah 
## 3 Hey Jude 30 Naa na na na na na na, na na na na, hey Jude 
## 4 Hey Jude 31 Naa na na na na na na, na na na na, hey Jude 
## 5 Hey Jude 32 Naa na na na na na na, na na na na, hey Jude 
## 6 Hey Jude 33 Naa na na na na na na, na na na na, hey Jude 
## 7 Hey Jude 35 Naa na na na na na na (Na na na), na na na na, hey Jude 
## 8 Hey Jude 37 Naa na na na na na na (Yeah yeah yeah), na na na na, hey J…
## 9 Hey Jude 38 (You know you can make, Jude Jude, You're not gonna break …
## 10 Hey Jude 39 Naa na (Don't make it bad Jude) na na na na na (Take a sad…
## # … with 11 more rows
```

---

## Extract

```r
str_subset(string = hey_jude$lyric, pattern = "[:punct:]") %>%
  str_extract(pattern = "[:punct:]")
```

```
##  [1] "," "," "," "'" "'" "," "," "(" "(" "," "'" "'" "," "'" "," "," "," "," ","
## [20] "(" "(" "(" "(" "(" "(" "," "," "," "," "," "(" "," "," "(" "(" "," "," ","
```

---

## Extract

```r
str_subset(string = hey_jude$lyric, pattern = "[:punct:]") %>%
  str_extract_all(pattern = "[:punct:]")
```

```
## [[1]]
## [1] "," "'"
## 
## [[2]]
## [1] "," "'"
## 
## [[3]]
## [1] "," ","
## 
## [[4]]
## [1] "'"
## 
## [[5]]
## [1] "'"
## 
## [[6]]
## [1] "," "'"
## 
## [[7]]
## [1] ","
## 
## [[8]]
## [1] "(" ")"
## 
## [[9]]
## [1] "(" ")"
## 
## [[10]]
## [1] "," ","
## 
## [[11]]
## [1] "'"
## 
## [[12]]
## [1] "'" "'" "," "," "'"
## 
## [[13]]
## [1] "," "'"
## 
## [[14]]
## [1] "'" "(" "," "!" ")"
## 
## [[15]]
## [1] ","
## 
## [[16]]
## [1] "," ","
## 
## [[17]]
## [1] "," ","
## 
## [[18]]
## [1] "," ","
## 
## [[19]]
## [1] "," ","
## 
## [[20]]
## [1] "(" ")"
## 
## [[21]]
## [1] "(" ")" "," ","
## 
## [[22]]
## [1] "(" ")"
## 
## [[23]]
## [1] "(" ")" "," ","
## 
## [[24]]
## [1] "(" "," "," "'" ")"
## 
## [[25]]
## [1] "(" "'" ")" "(" ")" "," ","
## 
## [[26]]
## [1] ","
## 
## [[27]]
## [1] "," ","
## 
## [[28]]
## [1] "," ","
## 
## [[29]]
## [1] "," ","
## 
## [[30]]
## [1] "," ","
## 
## [[31]]
## [1] "(" ")"
## 
## [[32]]
## [1] "," ","
## 
## [[33]]
## [1] "," ","
## 
## [[34]]
## [1] "(" ")" "," ","
## 
## [[35]]
## [1] "(" ")"
## 
## [[36]]
## [1] "," "," "(" ")"
## 
## [[37]]
## [1] "," ","
## 
## [[38]]
## [1] "," ","
```

---

## Extract

```r
str_view(hey_jude$lyric, pattern = "(?<= let )\\w+")
```

<div id="htmlwidget-093173cbf678bf8693be" style="width:960px;height:100%;" class="str_view html-widget"></div>
<script type="application/json" data-for="htmlwidget-093173cbf678bf8693be">{"x":{"html":"<ul>\n <li>Hey Jude, don't make it bad<\/li>\n <li>Take a sad song and make it better<\/li>\n <li>Remember to let her<\/span> into your heart<\/li>\n <li>Then you can start to make it better<\/li>\n <li>Hey Jude, don't be afraid<\/li>\n <li>You were made to go out and get her<\/li>\n <li>The minute you let her<\/span> under your skin<\/li>\n <li>Then you begin to make it better<\/li>\n <li>And anytime you feel the pain, hey Jude, refrain<\/li>\n <li>Don't carry the world upon your shoulders<\/li>\n <li>For well you know that it's a fool who plays it cool<\/li>\n <li>By making his world a little colder<\/li>\n <li>Na na na na na na na na na na<\/li>\n <li>Hey Jude, don't let me<\/span> down<\/li>\n <li>You have found her, now go and get her<\/li>\n <li>(Let it out and let it<\/span> in)<\/li>\n <li>Remember (Hey Jude) to let her<\/span> into your heart<\/li>\n <li>Then you can start to make it better<\/li>\n <li>So let it<\/span> out and let it in, hey Jude, begin<\/li>\n <li>You're waiting for someone to perform with<\/li>\n <li>And don't you know that it's just you, hey Jude, you'll do<\/li>\n <li>The movement you need is on your shoulder<\/li>\n <li>Na na na na na na na na na yeah<\/li>\n <li>Hey Jude, don't make it bad<\/li>\n <li>Take a sad song and make it better<\/li>\n <li>Remember to let her<\/span> under your skin<\/li>\n <li>Then you'll begin to make it (Whoa, fucking hell!)<\/li>\n <li>Better better better better better better, oh<\/li>\n <li>Yeah yeah yeah yeah yeah yeah yeah<\/li>\n <li>Naa na na na na na na, na na na na, hey Jude<\/li>\n <li>Naa na na na na na na, na na na na, hey Jude<\/li>\n <li>Naa na na na na na na, na na na na, hey Jude<\/li>\n <li>Naa na na na na na na, na na na na, hey Jude<\/li>\n <li>(Jude Judy Judy Judy Judy Judy owwwww wowww)<\/li>\n <li>Naa na na na na na na (Na na na), na na na na, hey Jude<\/li>\n <li>(Jude Jude Jude Jude Jude)<\/li>\n <li>Naa na na na na na na (Yeah yeah yeah), na na na na, hey Jude<\/li>\n <li>(You know you can make, Jude Jude, You're not gonna break it)<\/li>\n <li>Naa na (Don't make it bad Jude) na na na na na (Take a sad song and make it better), na na na na, hey Jude<\/li>\n <li>Hey Jude, hey Jude wowwwwww<\/li>\n <li>Naa na na na na na na, na na na na, hey Jude<\/li>\n <li>Naa na na na na na na, na na na na, hey Jude<\/li>\n <li>Jude Jude Jude Jude Jude Jude<\/li>\n <li>Naa na na na na na na, na na na na, hey Jude<\/li>\n <li>Naa na na na na na na, na na na na, hey Jude<\/li>\n <li>(Na na na na na na na na na na na na)<\/li>\n <li>Naa na na na na na na, na na na na, hey Jude<\/li>\n <li>Naa na na na na na na, na na na na, hey Jude<\/li>\n <li>Naa na na na na na na (Make it Jude), na na na na, hey Jude<\/li>\n <li>(Yeah yeah yeah yeah yeah yeah yeah)<\/li>\n <li>Naa na na na na na na, na na na na, hey Jude(Go listen to ya ma ma ma ma ma ma ma ma)<\/li>\n <li>Naa na na na na na na, na na na na, hey Jude<\/li>\n <li>Naa na na na na na na, na na na na, hey Jude<\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script>

---

## Extract

```r
hey_jude %>%
 filter(str_detect(lyric, "let")) %>%
 mutate(after = str_extract(lyric, "(?<= let )\\w+"))
```

```
## # A tibble: 7 x 4
## track_title line lyric after
## <chr> <int> <chr> <chr>
## 1 Hey Jude 3 Remember to let her into your heart her 
## 2 Hey Jude 7 The minute you let her under your skin her 
## 3 Hey Jude 14 Hey Jude, don't let me down me 
## 4 Hey Jude 16 (Let it out and let it in) it 
## 5 Hey Jude 17 Remember (Hey Jude) to let her into your heart her 
## 6 Hey Jude 19 So let it out and let it in, hey Jude, begin it 
## 7 Hey Jude 26 Remember to let her under your skin her
```

---

## Replace

```r
hey_kelly <- hey_jude %>%
 mutate(lyric = str_replace_all(lyric, 
 "Judy|Jude",
 "Kelly"))
hey_kelly
```

```
## # A tibble: 53 x 3
## track_title line lyric 
## <chr> <int> <chr> 
## 1 Hey Jude 1 Hey Kelly, don't make it bad 
## 2 Hey Jude 2 Take a sad song and make it better 
## 3 Hey Jude 3 Remember to let her into your heart 
## 4 Hey Jude 4 Then you can start to make it better 
## 5 Hey Jude 5 Hey Kelly, don't be afraid 
## 6 Hey Jude 6 You were made to go out and get her 
## 7 Hey Jude 7 The minute you let her under your skin 
## 8 Hey Jude 8 Then you begin to make it better 
## 9 Hey Jude 9 And anytime you feel the pain, hey Kelly, refrain
## 10 Hey Jude 10 Don't carry the world upon your shoulders 
## # … with 43 more rows
```

---

## Split

```r
str_split(hey_jude$lyric[1], " ")
```

```
## [[1]]
## [1] "Hey"   "Jude," "don't" "make"  "it"    "bad"
```

* Will seen a tidier way to do this with `tidytext` on Thursday.

---

## Up Next:

Now that we now how to handle text/strings as data, let's do some text analysis with `tidytext`.

Topics:

* Tokenizing to a tidy format
* Word frequencies
* Word clouds
* Sentiment analysis