Shiny is a package from RStudio that makes it incredibly easy to build interactive web applications with R. Have a look at some of the applications built using Shiny and perhaps you'll be as impressed as me. I will set up a local Shiny server on Ubuntu (12.04) running under VirtualBox. You don't actually need to install the server, to build Shiny applications, however some day I would like host my own Shiny server with a bunch of applications that I've built. To get started, let's check out the official tutorial on using Shiny. Fire up R and install the package:
install.packages("shiny")
library(shiny)
#run the first example
runExample("01_hello")
A web browser screenshot of what you would see when you run the example.
Shiny applications have two components: a user-interface definition (ui.R) and a server script (server.R):
ui.R
library(shiny)
# Define UI for application that plots random distributions
shinyUI(pageWithSidebar(
# Application title
headerPanel("Hello Shiny!"),
# Sidebar with a slider input for number of observations
sidebarPanel(
sliderInput("obs",
"Number of observations:",
min = 1,
max = 1000,
value = 500)
),
# Show a plot of the generated distribution
mainPanel(
plotOutput("distPlot")
)
))
server.R
library(shiny)
# Define server logic required to generate and plot a random distribution
shinyServer(function(input, output) {
# Expression that generates a plot of the distribution. The expression
# is wrapped in a call to renderPlot to indicate that:
#
# 1) It is "reactive" and therefore should be automatically
# re-executed when inputs change
# 2) Its output type is a plot
#
output$distPlot <- renderPlot({
# generate an rnorm distribution and plot it
dist <- rnorm(input$obs)
hist(dist)
})
})
Installing the Shiny server
Following the instructions from the Shiny installation guide for Ubuntu:
#if you don't have R installed already
sudo apt-get install r-base
#install dependencies
sudo apt-get install gdebi-core
#download the shiny server package
wget http://download3.rstudio.org/ubuntu-12.04/x86_64/shiny-server-0.4.0.8-amd64.deb
#install
sudo gdebi shiny-server-0.4.0.8-amd64.deb
#install shiny package
sudo su - \
-c "R -e \"install.packages('shiny', repos='http://cran.rstudio.com/')\""
When you start the server, it will attempt to load its configuration from /etc/shiny-server/shiny-server.conf, which you need to create. For now my /etc/shiny-server/shiny-server.conf file contains the default configuration:
#create the directory
sudo mkdir /etc/shiny-server
#copy and paste the below
sudo vi /etc/shiny-server/shiny-server.conf
# Define the user we should use when spawning R Shiny processes
run_as shiny;
# Define a top-level server which will listen on a port
server {
# Instruct this server to listen on port 3838
listen 3838;
# Define the location available at the base URL
location / {
# Run this location in 'site_dir' mode, which hosts the entire directory
# tree at '/srv/shiny-server'
site_dir /srv/shiny-server;
# Define where we should put the log files for this location
log_dir /var/log/shiny-server;
# Should we list the contents of a (non-Shiny-App) directory when the user
# visits the corresponding URL?
directory_index on;
}
}
The default configuration above will create a single server listening on port 3838, serving any application contained within /srv/shiny-server/ at the root URL (/).
Let's create a new directory inside /srv/shiny-server/ called shinyApp1 and save the ui.R and server.R files from the start of this post in this directory.
ls /srv/shiny-server/shinyApp1 server.R ui.R
To start the server (and other releated commands):
#start server sudo start shiny-server #stop server sudo stop shiny-server #restart server sudo restart shiny-server #reload sudo reload shiny-server #check status status shiny-server
After we've started the server, if we direct our browser to http://localhost:3838/shinyApp1/, we should see this:
Let's try another application taken from the Shiny page on Rstudio and save the two components inside /srv/shiny-server/shinyApp2:
ui.R
library(shiny)
shinyUI(bootstrapPage(
selectInput(inputId = "n_breaks",
label = "Number of bins in histogram (approximate):",
choices = c(10, 20, 35, 50),
selected = 20),
checkboxInput(inputId = "individual_obs",
label = strong("Show individual observations"),
value = FALSE),
checkboxInput(inputId = "density",
label = strong("Show density estimate"),
value = FALSE),
plotOutput(outputId = "main_plot", height = "300px"),
# Display this only if the density is shown
conditionalPanel(condition = "input.density == true",
sliderInput(inputId = "bw_adjust",
label = "Bandwidth adjustment:",
min = 0.2, max = 2, value = 1, step = 0.2)
)
))
server.R
library(shiny)
shinyServer(function(input, output) {
output$main_plot <- renderPlot({
hist(faithful$eruptions,
probability = TRUE,
breaks = as.numeric(input$n_breaks),
xlab = "Duration (minutes)",
main = "Geyser eruption duration")
if (input$individual_obs) {
rug(faithful$eruptions)
}
if (input$density) {
dens <- density(faithful$eruptions,
adjust = input$bw_adjust)
lines(dens, col = "blue")
}
})
})
Building my own application
The bare minimum required for the ui.R and server.R files are:
ui.R
library(shiny)
# Define UI for miles per gallon application
shinyUI(pageWithSidebar(
# Application title
headerPanel("Title"),
sidebarPanel(),
mainPanel()
))
server.R
library(shiny)
shinyServer(function(input, output) {
})
To test run these files within R, use the runApp() function specifying the location of the ui.R and server.r files:
library(shiny)
setwd("C:/Users//Dave/Desktop/shiny/")
runApp('.')
I'll build an application using the iris dataset and allowing myself to produce scatter plots between the 4 leaf measurements. Here's the dataset, if you aren't familiar with it already:
head(iris) Sepal.Length Sepal.Width Petal.Length Petal.Width Species 1 5.1 3.5 1.4 0.2 setosa 2 4.9 3.0 1.4 0.2 setosa 3 4.7 3.2 1.3 0.2 setosa 4 4.6 3.1 1.5 0.2 setosa 5 5.0 3.6 1.4 0.2 setosa 6 5.4 3.9 1.7 0.4 setosa
And here's the code I wrote:
ui.R
library(shiny)
# Define UI for iris application
shinyUI(pageWithSidebar(
# Application title
headerPanel("Using Shiny with the iris dataset"),
# Sidebar with controls to select the variable to plot against mpg
# and to specify whether outliers should be included
sidebarPanel(
selectInput("variable", "First variable:",
list("Sepal length" = "Sepal.Length",
"Sepal width" = "Sepal.Width",
"Petal length" = "Petal.Length",
"Petal width" = "Petal.Width")),
selectInput("variable2", "Second variable:",
list("Sepal length" = "Sepal.Length",
"Sepal width" = "Sepal.Width",
"Petal length" = "Petal.Length",
"Petal width" = "Petal.Width"))
),
mainPanel(
h3(textOutput("caption")),
plotOutput("plot")
)
))
server.R
library(shiny)
library(datasets)
library(ggplot2)
data <- iris
# Define server logic required to plot variables
shinyServer(function(input, output) {
# Create a reactive text
text <- reactive({
paste(input$variable, 'versus', input$variable2)
})
# Return as text the selected variables
output$caption <- renderText({
text()
})
# Generate a plot of the requested variables
output$plot <- renderPlot({
p <- ggplot(data, aes_string(x=input$variable, y=input$variable2, colour="Species")) + geom_point()
print(p)
})
})
And here are two screenshots of my new Shiny app!
To get it working on the shiny server, follow the instructions above and install ggplot2:
sudo su - \
-c "R -e \"install.packages('ggplot2', repos='http://cran.ism.ac.jp/')\""
Now goto http://localhost:3838/my_app/ and voila!
Conclusions
Shiny is awesome!
Further reading
The Shiny tutorial
This work is licensed under a Creative Commons
Attribution 4.0 International License.
Great instructions, but what is the command to save ui.R and server.R into the directory.
Use any text editor you prefer to save the R scripts. You could use Word, Notepad, Vi, or RStudio.
I understand up to sudo mkdir /etc/shiny-server, but are you actually creating these directories on your machine, or on the Ubuntu machine? If it is not on your machine, then how can you save it directly from RStudio?
Everything is set up on the server (the Ubuntu machine). When I said RStudio, I meant you can use the text editor within it to save the code; all you need is a text editor to save the code in the directories. I use Vi, so the command is
1. vi ui.R
2. press i
3. copy and paste the code
4. press escape
5. then hold shift and press z twice, i.e. ZZ
Thanks a lot for this post. It is really helped me execute shiny on server!