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<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" lang="" xml:lang="">
<head>
<title>Touring tidyverse</title>
<meta charset="utf-8" />
<meta name="author" content="Misha Balyasin" />
<link href="libs/remark-css/default.css" rel="stylesheet" />
<link href="libs/remark-css/default-fonts.css" rel="stylesheet" />
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<textarea id="source">
class: center, middle, inverse, title-slide
# Touring tidyverse
## tidy data + tidyr
### Misha Balyasin
---
# tidyverse
> The tidyverse is an __opinionated__ collection of R packages designed for data science. All packages share an underlying design philosophy, grammar, and data structures.
All things tidyverse: https://www.tidyverse.org/
---
# Tidy manifesto<sup>1</sup>
1. Reuse existing data structures.
--
2. Compose simple functions with the pipe.
- Strive to keep functions as simple as possible.
- Avoid mixing side-effects with transformations.
- Function names should be verbs.
--
3. Embrace R typical functional programming.
- Immutable objects and copy-on-modify semantics.
- The generic functions provided by S3 and S4.
- Tools that abstract over for-loops.
--
4. Design for humans.
- Invest time in naming your functions.
- Favour explicit, lengthy names, over short, implicit, names.
- Think about how autocomplete can also make an API that’s easy to write.
.footnote[
[1] https://cran.r-project.org/web/packages/tidyverse/vignettes/manifesto.html
]
---
background-image: url(http://r4ds.had.co.nz/diagrams/data-science.png)
background-size: 800px
# tidyverse in a picture
---
background-image: url(https://avatars1.githubusercontent.com/u/22032646?v=3&s=400)
background-size: 100px
background-position: 90% 8%
# Core tidyverse
```r
#install.packages("tidyverse")
library(tidyverse)
```
```
## Registered S3 methods overwritten by 'ggplot2':
## method from
## [.quosures rlang
## c.quosures rlang
## print.quosures rlang
```
```
## ── Attaching packages ──────────────────────────────────────────────────────────────────────────────── tidyverse 1.2.1 ──
```
```
## ✔ ggplot2 3.1.1 ✔ purrr 0.3.2
## ✔ tibble 2.1.3 ✔ dplyr 0.8.1.9000
## ✔ tidyr 0.8.3.9000 ✔ stringr 1.4.0.9000
## ✔ readr 1.3.1 ✔ forcats 0.4.0
```
```
## ── Conflicts ─────────────────────────────────────────────────────────────────────────────────── tidyverse_conflicts() ──
## ✖ dplyr::filter() masks stats::filter()
## ✖ dplyr::lag() masks stats::lag()
```
---
class: center, middle
# Tidy data
---
# Tidy data
1. Each variable forms a column.
2. Each observation forms a row.
3. Each type of observational unit forms a table.
This is Codd's 3rd normal form.
---
background-image: url(https://www.rstudio.com/wp-content/uploads/2014/04/tidyr.png)
background-size: 100px
background-position: 90% 8%
# tidyr
1. tidyr replaces reshape2 (2010-2014) and reshape (2005-2010).
2. Current version - 0.8.3.9000 (dev version!).
3. https://github.com/tidyverse/tidyr
4. __Hadley Wickham__ and Lionel Henry are two main contributors.
---
# Examples
```r
knitr::kable(head(tidyr::table2), format = "html")
```
<table>
<thead>
<tr>
<th style="text-align:left;"> country </th>
<th style="text-align:right;"> year </th>
<th style="text-align:left;"> type </th>
<th style="text-align:right;"> count </th>
</tr>
</thead>
<tbody>
<tr>
<td style="text-align:left;"> Afghanistan </td>
<td style="text-align:right;"> 1999 </td>
<td style="text-align:left;"> cases </td>
<td style="text-align:right;"> 745 </td>
</tr>
<tr>
<td style="text-align:left;"> Afghanistan </td>
<td style="text-align:right;"> 1999 </td>
<td style="text-align:left;"> population </td>
<td style="text-align:right;"> 19987071 </td>
</tr>
<tr>
<td style="text-align:left;"> Afghanistan </td>
<td style="text-align:right;"> 2000 </td>
<td style="text-align:left;"> cases </td>
<td style="text-align:right;"> 2666 </td>
</tr>
<tr>
<td style="text-align:left;"> Afghanistan </td>
<td style="text-align:right;"> 2000 </td>
<td style="text-align:left;"> population </td>
<td style="text-align:right;"> 20595360 </td>
</tr>
<tr>
<td style="text-align:left;"> Brazil </td>
<td style="text-align:right;"> 1999 </td>
<td style="text-align:left;"> cases </td>
<td style="text-align:right;"> 37737 </td>
</tr>
<tr>
<td style="text-align:left;"> Brazil </td>
<td style="text-align:right;"> 1999 </td>
<td style="text-align:left;"> population </td>
<td style="text-align:right;"> 172006362 </td>
</tr>
</tbody>
</table>
---
# Overview of the API
```r
funs <- getNamespaceExports("tidyr")
funs[!grepl(x = funs, pattern = "_$")]
```
```
## [1] "chop" "full_seq" "replace_na"
## [4] "gather" "expand_grid" "expand"
## [7] "nest" "as_tibble" "tibble"
## [10] "one_of" "everything" "fill"
## [13] "drop_na" "pivot_wider_spec" "matches"
## [16] "extract_numeric" "uncount" "hoist"
## [19] "unite" "separate" "crossing"
## [22] "nesting" "ends_with" "starts_with"
## [25] "tidyr_legacy" "unpack" "last_col"
## [28] "unnest_auto" "unchop" "unnest_wider"
## [31] "unnest_longer" "pivot_longer" "pivot_wider"
## [34] "separate_rows" "pivot_longer_spec" "contains"
## [37] "unnest" "extract" "spread"
## [40] "complete" "%>%" "tribble"
## [43] "num_range" "pack"
```
---
# New features
1. Pivoting (inspired by `cdata` and `data.table`).
1. Rectangling.
1. https://github.com/tidyverse/tidyr/blob/master/NEWS.md
---
<div class="countdown blink-colon noupdate-30" id="timer_5d022ea2" style="top:0;right:0;bottom:0;left:0;margin:5%;padding:20%;font-size:8em;line-height:1.25;" data-warnwhen="0">
<code class="countdown-time"><span class="countdown-digits minutes">05</span><span class="countdown-digits colon">:</span><span class="countdown-digits seconds">00</span></code>
</div>
---
# Resources
1. http://r4ds.had.co.nz/index.html
2. http://tidyr.tidyverse.org/
3. http://vita.had.co.nz/papers/tidy-data.html
4. https://www.r-exercises.com/2017/06/22/data-wrangling-reshaping/
6. https://www.daeconomist.com/post/2018-05-15-spread/
7. https://github.com/MangoTheCat/tidyshiny/
8. https://github.com/rstudio/cheatsheets/blob/master/data-import.pdf
9. https://github.com/rstudio/webinars/tree/master/54-row-oriented-work - some examples with nesting
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