Shiny Application Layout Guide

Overview

Shiny includes a number of facilities for laying out the components of an application. The default layout is a simple page with a sidebar and main output area and this serves many applications well. However, as applications get larger, more complex, or acquire more customized presentation requirements the simple default layout is too limiting. This guide describes the Shiny features that can be used to create more sophisticated component layouts, including:

1. Creating tabsets with the tabsetPanel() function

2. Creating applications with multiple top-level components using the navbarPage() function.

3. Custom layout of user interface elements using rows and columns.

Note that the functions described here require a development version of the Shiny package. You can install this version as follows:

devtools::install_github("rstudio/shiny", ref = "feature/bootstrap-layout")

Sidebar Layout

The sidebar layout is a useful starting point for considering more complex layouts. This layout provides a sidebar for inputs and a large main area for output:

Here's the code used to create this layout:

shinyUI(fluidPage(

  titlePanel("Hello Shiny!"),

  sidebarLayout(

    sidebarPanel(
      sliderInput("obs", "Number of observations:",  
                  min = 1, max = 1000, value = 500)
    ),

    mainPanel(
      plotOutput("distPlot")
    )
  )
))

Note that the sidebar can be positioned to the left (the default) or right of the main area. For example, to position the sidebar to the right you would use this code:

sidebarLayout(position = "right",
              
  sidebarPanel(
    # Inputs excluded for brevity
  ),
  mainPanel(
    # Outputs excluded for brevity 
  )
)

Tabsets

Often applications need to subdivide their user-interface into discrete sections. This can be accomplished using the tabsetPanel() function. For example:

The code required to create this UI is:

shinyUI(fluidPage(

  titlePanel("Tabsets"),

  sidebarLayout(
    
    sidebarPanel(
      # Inputs excluded for brevity
    ),
  
    mainPanel(
      tabsetPanel(
        tabPanel("Plot", plotOutput("plot")), 
        tabPanel("Summary", verbatimTextOutput("summary")), 
        tabPanel("Table", tableOutput("table"))
      )
    )
  )
))

Tabs can be located above (the default), below, left, or to the right of tab content. For example, to position the tabs below the tab content you would use this code:

tabsetPanel(position = "below",
  tabPanel("Plot", plotOutput("plot")), 
  tabPanel("Summary", verbatimTextOutput("summary")), 
  tabPanel("Table", tableOutput("table"))
)

Navbar Pages

You may want to create a Shiny application that consists of multiple distinct sub-components (each with their own sidebar, tabsets, or other layout constructs). The navbarPage() function creates an application with a standard Bootstrap Navbar at the top. For example:

shinyUI(navbarPage("My Application",
  tabPanel("Component 1"),
  tabPanel("Component 2"),
  tabPanel("Component 3")
))

Note that the Shiny tabPanel() is used to specify the navigable components.

Secondary Navigation

You can add a second level of navigation to the page by using the navbarMenu() function. This adds a menu to the top level navbar which can in turn refer to additional tabPanels.

shinyUI(navbarPage("My Application",
  tabPanel("Component 1"),
  tabPanel("Component 2"),
  navbarMenu("More",
    tabPanel("Sub-Component A"),
    tabPanel("Sub-Component B"))
))

Additional Options

There are several other arguments to navbarPage() that provide additional measures of customization:

Argument	Description
header	Tag of list of tags to display as a common header above all tabPanels.
footer	Tag or list of tags to display as a common footer below all tabPanels
inverse	TRUE to use a dark background and light text for the navigation bar
collapsable	TRUE to automatically collapse the navigation elements into a menu when the width of the browser is less than 940 pixels (useful for viewing on smaller touchscreen device)

Grid Layouts

The familiar sidebarLayout() described above makes use of Shiny's lower-level grid layout functions. Grid rows are created by the fluidRow() function and include columns defined by the column() function. Column widths are based on the Bootstrap 12-wide grid system, so should add up to 12 within a fluidRow() container.

To illustrate, here's the standard sidebar layout implemented using the fluidRow(), column() and wellPanel() functions:

shinyUI(fluidPage(

  titlePanel("Hello Shiny!"),

  fluidRow(
  
    column(4,
      wellPanel(
        sliderInput("obs", "Number of observations:",  
                    min = 1, max = 1000, value = 500)
      )       
    ),

    column(8,
      plotOutput("distPlot")
    )
  )
))

The first parameter to the column() function is it's width (out of a total of 12 columns). It's also possible to offset the position of columns to achieve more precise control over the location of UI elements. You can move columns to the right by adding the offset parameter to the column() function. Each unit of offset increases the left-margin of a column by a whole column.

Here's an example of a UI with a plot at the top and three columns at the bottom that contain the inputs that drive the plot:

The code required to implement this UI is as follows:

library(shiny)
library(ggplot2)

dataset <- diamonds

shinyUI(fluidPage(

  title = "Diamonds Explorer",
  
  plotOutput('plot'),
  
  hr(),

  fluidRow(
    column(3,
      h4("Diamonds Explorer"),
      sliderInput('sampleSize', 'Sample Size', 
                  min=1, max=nrow(dataset), value=min(1000, nrow(dataset)), 
                  step=500, round=0),
      br(),
      checkboxInput('jitter', 'Jitter'),
      checkboxInput('smooth', 'Smooth')
    ),
    column(4, offset = 1,
      selectInput('x', 'X', names(dataset)),
      selectInput('y', 'Y', names(dataset), names(dataset)[[2]]),
      selectInput('color', 'Color', c('None', names(dataset)))
    ),
    column(4,
      selectInput('facet_row', 'Facet Row', c(None='.', names(dataset))),
      selectInput('facet_col', 'Facet Column', c(None='.', names(dataset)))
    )
  )
))

There are a few important things to note here:

1. The inputs are at the bottom and broken into three columns of varying widths.

2. The offset parameter is used on the center input column to provide custom spacing between the first and second columns.

3. The page doesn't include a titlePanel() so the title is specified as an explicit argument to fluidPage().

Grid layouts can be used anywhere within a fluidPage() and can even be nested within each other.

Fluid vs. Fixed Layout

There are two types of Bootstrap grids, fluid and fixed. The examples so far have used the fluid grid system exclusively and that's the system that's recommended for most applications (and the default for Shiny functions like navbarPage() and sidebarLayout()).

Both grid systems use a flexibly sub-dividable 12-column grid for layout. The fluid system always occupies the full width of the web page and re-sizes it's components dynamically as the size of the page changes. The fixed system occupies a fixed width of 940 pixels by default and may assume other widths when Bootstrap responsive layout kicks in (e.g. when on a tablet).

The following sections are a translation of the official Bootstrap 2 grid system documentation, with HTML code replaced by R code.

Fluid Grid System

The Bootstrap grid system utilizes 12 columns which can be flexibly subdivided into rows and columns. To create a layout based on the fluid system you use the fluidPage() function. To create rows within the grid you use the fluidRow() function; to create columns within rows you use the column() function.

For example, consider this high level page layout (the numbers displayed are columns out of a total of 12):

To create this layout in a Shiny application you'd use the following code (note that the column widths within the fluid row add up to 12):

shinyUI(fluidPage(
  fluidRow(
    column(2,
      "sidebar"
    ),
    column(10,
      "main"
    )
  )
))

Column Offsetting

It's also possible to offset the position of columns to achieve more precise control over the location of UI elements. Move columns to the right by adding the offset parameter to the column() function. Each unit of offset increases the left-margin of a column by a whole column. Consider this layout:

To create this layout in a Shiny application you'd using the following code:

shinyUI(fluidPage(
  fluidRow(
    column(4,
      "4"
    ),
    column(4, offset = 4,
      "4 offset 4"
    )      
  ),
  fluidRow(
    column(3, offset = 3,
      "3 offset 3"
    ),
    column(3, offset = 3,
      "3 offset 3"
    )  
  )
))

Column Nesting

When you nest columns within a fluid grid, each nested level of columns should add up to 12 columns. This is because the fluid grid uses percentages, not pixels, for setting widths. Consider this page layout:

To create this layout in a Shiny application you'd use the following code:

shinyUI(fluidPage(
  fluidRow(
    column(12,
      "Fluid 12",
      fluidRow(
        column(6,
          "Fluid 6",
          fluidRow(
            column(6, 
              "Fluid 6"),
            column(6,
              "Fluid 6")
          )
        ),
        column(width = 6,
          "Fluid 6")
      )
    )
  )
))

Note that each time a fluidRow() is introduced the columns within the row add up to 12.

Fixed Grid System

The fixed grid system also utilizes 12 columns, and maintains a fixed width of 940 pixels by default. If Bootstrap responsive features are enabled (they are by default in Shiny) then the grid will also adapt to be 724px or 1170px wide depending on your viewport (e.g. when on a tablet).

The main benefit of a fixed grid is that it provides stronger guarantees about how users will see the various elements of your UI laid out (this is because it's not being dynamically laid out according to the width of the browser). The main drawback is that it's a bit more complex to work with. In general we recommend using fluid grids unless you absolutely require the lower level layout control afforded by a fixed grid.

Using Fixed Grids

Using fixed grids in Shiny works almost identically to fluid grids. Here are the differences to keep in mind:

1. You use the fixedPage() and fixedRow() functions to build the grid.

2. Rows can nest, but should always include a set of columns that add up to the number of columns of their parent (rather than resetting to 12 at each nesting level as they do in fluid grids).

Here's the code for a fixed grid version of the simple sidebar layout shown earlier:

shinyUI(fixedPage(
  fixedRow(
    column(2,
      "sidebar"
    ),
    column(10,
      "main"
    )
  )
))

Column Nesting

In fixed grids the width of each nested column must add up to the number of columns in their parent. Here's a fixedRow() with a 9-wide column that contains two other columns of width 6 and 3:

The create this row within a Shiny application you'd use the following code:

fixedRow(
  column(9,
    "Level 1 column",
    fixedRow(
      column(6,
        "Level 2"
      ),
      column(3,
        "Level 2"
      )
    )
  )
)

Note that the total size of the nested columns is 9, the same as their parent column.

Responsive Design

The Bootstrap grid system supports responsive css, which enables your application to automatically adapt it's layout for viewing on different sized devices. Responsive layout includes the following:

1. Modifying the width of columns in the grid
2. Stack elements instead of float wherever necessary
3. Resize headings and text to be more appropriate for devices

Responsive layout is enabled by default for all Shiny page types. To disable responsive layout you should pass responsive = FALSE to the fluidPage() or fixedPage() function.

Supported Devices

When responsive layout is enabled here is how the Bootstrap grid system adapts to various devices:

	Layout width	Column width	Gutter width
Large display	1200px and up	70px	30px
Default	980px and up	60px	20px
Portrait tablets	768px and above	42px	20px
Phones to tablets	767px and below	Fluid (no fixed widths)	Fluid (no fixed widths)
Phones	480px and below	Fluid (no fixed widths)	Fluid (no fixed widths)

Note that on smaller screen sizes fluid columns widths are used automatically even if the page uses fixed grid layout.