Understanding how to stack shinyWidgets radioGroupButtons and shiny fileInput widgets without adding unnecessary whitespace in R applications with Shiny.

Understanding the Problem: Space around shinyWidgets radioGroupButtons and shiny fileInput?

In this blog post, we’ll delve into a common issue with shinyWidgets and shiny applications in R. Specifically, we’ll explore ways to adjust the space around radioGroupButtons and fileInput widgets.

Problem Statement

The question arises when users want to stack fileInput and radioGroupButtons instances on top of each other without adding unnecessary whitespace between them. This is a common requirement in data visualization and file upload applications, where the user needs to select an input type (e.g., file or radio button) and then upload or select a value.

Understanding shinyWidgets

Before we dive into solutions, let’s briefly discuss shinyWidgets, which is a package for creating reusable UI components in R. It provides pre-built widgets that can be easily integrated into shiny applications. The radioGroupButtons widget allows users to select options from a group of choices.

Understanding shiny

shiny is an open-source web application framework for R that enables the creation of interactive, web-based UIs. It uses HTML, CSS, and JavaScript under the hood to render user interfaces.

Current Solution: A Workaround

The current solution involves adding some CSS styling to adjust the layout of fileInput and radioGroupButtons. By setting specific classes on these widgets, we can achieve a stacked layout without adding any additional whitespace.

ui = page_fillable(
  tags$head(
    tags$style(type="text/css", 
             ".radio_style .form-group {float:left; display:inline; width: 300px;}")),
  div(class='radio_style', 
   fileInput("fileInput1", label = NULL),
   radioGroupButtons("radioGroupButtons1", choices = c("TSV", "CSV", "XLSX"))
  ),
  div(class='radio_style', 
   fileInput("fileInput2", label = NULL),
   radioGroupButtons("radioGroupButtons2", choices = c("PDF", "PNG", "JPEG"))
  )
)

In the above code, we’ve added a CSS class radio_style to both fileInput and radioGroupButtons. This class sets the display property to inline, which allows these elements to be displayed next to each other without adding any whitespace.

Understanding CSS Positioning

To achieve a stacked layout, we need to understand how CSS positioning works. There are two main types of positioning: relative and absolute.

Relative Positioning: This type of positioning affects the position of an element relative to its parent element.
Absolute Positioning: This type of positioning affects the position of an element relative to its nearest positioned ancestor (i.e., another element with a fixed or absolute position).

We can use both relative and absolute positioning techniques to stack fileInput and radioGroupButtons.

Stacking fileInput and radioGroupButtons

To stack fileInput and radioGroupButtons, we’ll need to apply some CSS styles. One way to do this is by using a container element with a fixed width, which will serve as the parent for both widgets.

ui = page_fillable(
  tags$head(
    tags$style(type="text/css", 
             ".stacked-inputs {width: 300px; float:left; display:inline; margin-bottom: 10px;}")),
  div(class='stacked-inputs', 
   fileInput("fileInput1", label = NULL),
   radioGroupButtons("radioGroupButtons1", choices = c("TSV", "CSV", "XLSX"))
  ),
  div(class='stacked-inputs', 
   fileInput("fileInput2", label = NULL),
   radioGroupButtons("radioGroupButtons2", choices = c("PDF", "PNG", "JPEG"))
  )
)

In this code, we’ve added a new CSS class stacked-inputs, which sets the display property to inline and adds some margin to create space between widgets. We’ve then applied this class to both fileInput and radioGroupButtons.

Using Float and Clear

Another way to stack these widgets is by using float properties.

ui = page_fillable(
  tags$head(
    tags$style(type="text/css", 
             ".stacked-inputs {width: 300px; float:left; display:inline;}")),
  div(class='radio_style', 
   fileInput("fileInput1", label = NULL),
   radioGroupButtons("radioGroupButtons1", choices = c("TSV", "CSV", "XLSX")),
   clear
  ),
  div(class='radio_style', 
   fileInput("fileInput2", label = NULL),
   radioGroupButtons("radioGroupButtons2", choices = c("PDF", "PNG", "JPEG"))
  )
)

In this code, we’ve removed the margin-bottom style and instead added a clear element to reset the float property after each widget.

Conclusion

By understanding how CSS positioning works and applying specific styles to our UI elements, we can adjust the space around shinyWidgets radioGroupButtons and shiny fileInput? widgets. Whether you choose to use relative or absolute positioning techniques, stacking these widgets provides an efficient way to structure your UI applications.

Last modified on 2025-03-15