Shiny Apps

Today we will create interactive web applications via Shiny. Shiny allows you to do so without knowing HTML, JavaScript, CSS, etc…

We won't be harnessing the full power of Shiny (i.e. using server.R and ui.R files), but rather a simplified version using R Markdown.

For a tutorial on using Shiny fully see http://shiny.rstudio.com/tutorial/.

Rich Majerus is Vice President of Research of Third Coast Analytics: a consulting company which provides statistics, analysis, and data management services for higher education.

Go to the webpage and click on the map on the bottom left of the page. This was made via Shiny.

There are two chief components building a Shiny app:

• inputPanel: Where your app takes inputs and stores them in an object called input. Ex: text, numerical values, sliders, radio buttons, etc.
• renderSOMETHING: After processing the inputs and data, Shiny renders an output: plots, table, text, etc.

• Install and load the shiny package
• Go to File -> New File -> R Markdown -> Shiny
• Select “Shiny Document”
• Create a new directory and save the .Rmd file in that directory
• Click “Run Document”
• Focus only on the “Inputs and Outputs” example

The inputPanel( ... ) section takes in two inputs (separated by a comma):

• selectInput() which assigns a value to n_breaks based on a selection menu, formats the input box, and selects 20 as the default option.
• sliderInput() which assigns a value to bw_adjust based on a slider, formats the input box, and sets 1 as the default value.

Note:

• All possible inputPanel() options are listed in “Widgets” on the cheatsheet.
• Type ?selectInput, for example, to get a sense for the arguments.

The renderPlot({ ... }) plots a histogram of the eruptions from the Old Faithful Geyser data set faithful.

Note:

• The inputted n_breaks and bw_adjust, are stored within the input. For example, to interactively use n_breaks, we need to specify input$n_breaks.
• There are curly braces in the renderPlot({})
• All possible rendering options are listed in “render functions” on the cheatsheet
• Each type of rendering must be done separately

Add a menu input option that allows you to specify the color of the smoother line.

• Go to https://www.shinyapps.io/ and create an account.
• Go to https://www.shinyapps.io/admin/#/dashboard and complete Steps 1-3.
• In your outputed Shiny app pop-up page, click on “Publish” on the top right.

Add a radio button so that the user has the option can limit consideration to only one sex.

Another tutorial: http://rmarkdown.rstudio.com/authoring_shiny.html