Shiny Tutorial

## Introduction to Shiny

March 28, 2019
 Tami L Crawford
 tami.crawford@gmail.com

---

## Overview

<div class="chalkboard">
<ul>
<li>Basics
<li>Application/Input/Outputs/Layouts
<li>rstudio.cloud
<li>Demo/Example Apps (Birding, Gene Explorer, HTML Template)
<li>Reactivity
<li>Debugging
<li>Modules
</ul>

</div>

![](images/non_modules_slides.svg)

---

# Basics

- Open Source Web framework for building reactive web applications in R

![](images/shiny_app_diagram.png)

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- Install and Load Shiny
```
install.packages("shiny")
library(shiny)
```

- Single File (app.R) 
- Multiple Files (ui.R, server.R)(optional global.R, images, css, helper scripts, etc)
- in RStudio, can use New/New File/Shiny Web app

![](images/shiny_app_code_layout.png)

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### Application

![](images/app_input_output.png)

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## Inputs

![](images/inputs.png)

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## Input/Outputs

![](images/input_output.png)

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## Layouts

![](images/layouts.png)

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### Running Shiny App

```
shiny::runApp()
shiny::runApp("path/to/app.R")
```

- in RStudo, use RunApp Control

---

## rstudio.cloud

- Free to create account https://rstudio.cloud
- Runs RStudio in browser
- Create projects from scratch, from github, from an rstudio.cloud project

---

# Demo - Birding App

![](images/birding_app.png)

- <a href="https://sharleenw.shinyapps.io/hamilton_cbc_shiny/" target="_blank">Birding App</a> less than 150 lines of code | [Blog Post](https://sharleenw.rbind.io/post/hamilton_cbc_part_3/hamilton-christmas-bird-count-part-3/) | [RStudio.cloud](https://rstudio.cloud/project/284222) https://rstudio.cloud/project/284222

---

# Demo - Interactive Gene Explorer

![](images/interactive_gene_explorer.png)

- <a href="https://ginberg.shinyapps.io/gene_explorer/" target="_blank">Interactive Gene Explorer</a> ~ 500 lines of code Links: <a href="https://github.com/ginberg/gene_explorer" target="_blank">github</a> | <a href="https://canvasxpress.org/html/index.html" target="_blank">CanvasXpress</a> | <a href="https://blog.dominodatalab.com/large-visualizations-canvasxpress/">Large visualisations incanvasXpress</a>
| [rstudio.cloud](https://rstudio.cloud/project/284254) https://rstudio.cloud/project/284254

---

# Demo - HTML Template

![](images/uber_template_app.png)

- <a href="https://vivekkatial.shinyapps.io/uber_shiny/" target="_blank">Uber Explore - Shiny HTML Template Example</a> <a href="https://rstudio.cloud/project/258358" target="_blank">RStudio Cloud</a>

# Reactivity

![](images/reactive_diagram.png)

---

# Debugging

- Reload app when source changes

```
options(shiny.autoreload = TRUE)
```

Must manually restart when there's a compilation error
or when changes are in a module or code that is loaded via 'source'

---

# Reactivity Log

- Reactivity Log

```
devtools::install_github("rstudio/reactlog")

library(shiny)
library(reactlog)

# tell shiny to log reactivity
options("shiny.reactlog" = TRUE)

# run a shiny app
app <- system.file("examples/01_hello", package = "shiny")
runApp(app)

# once app has closed, display reactlog
show_reactlog()
```

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# Modules - the problem

![](images/non_modules_slides.svg)
See https://bit.ly/modules2019 (Effective Use of Shiny modules)

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## Modules - The Solution
![](images/modules_slide.svg)

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### Exploratory Regression Shiny App (ERSA)

```
library(ERSA) 
library(mlbench)
data(BostonHousing)
f <- lm(crim ~ . , data = BostonHousing)
exploreReg(f, BostonHousing)
```

[rstudio.cloud](https://rstudio.cloud/project/284586) https://rstudio.cloud/project/284586

![](images/ERSA_bostonhousing.png)

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# Sharing your app

- shinyapps.io
- runGitHub()
- rstudio.cloud

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## Links

- [Shiny Cheatsheet](https://shiny.rstudio.com/articles/cheatsheet.html)
- [Online Shiny Tutorial](https://www.rstudio.com/online-learning/#shiny_)
- Birding App [blog post](https://sharleenw.rbind.io/post/hamilton_cbc_part_3/hamilton-christmas-bird-count-part-3/)

- ExploreModels [github](https://github.com/WinVector/ExploreModels)
- Interactive Gen Explorer [git](https://github.com/ginberg/gene_explorer) | [rstudio.cloud](https://rstudio.cloud/project/243079) |  [shinyapps](https://ginberg.shinyapps.io/gene_explorer/)

- [ERSA Demo (rstudio.cloud)](https://rstudio.cloud/project/284586) https://rstudio.cloud/project/284586

- [Shiny in Produciton Talk RStudio Conf 2019](https://resources.rstudio.com/rstudio-conf-2019/shiny-in-production-principles-practices-and-tools-joe-cheng) which describes CranWhales [github](https://github.com/rstudio/cranwhales.git)

- [Effective Use of Shiny modules - RStudio Conf](https://resources.rstudio.com/rstudio-conf-2019/effective-use-of-shiny-modules-in-application-development)

- [Reactlog 2.0: Debugging the state of Shiny - RStudio Confg 2019](https://resources.rstudio.com/rstudio-conf-2019/reactlog-2-0-debugging-the-state-of-shiny)

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![](images/shiny_logo.png)