I present a method for reactively updating a table of acronyms from a Shiny interactive timeline using renderDataTable and timevis. The method is used in the new Shiny app, stratvis.
The stratvis app
stratvis Shiny app provides a rich and fully interactive timeline
visualization of hierarchical items (e.g. strategy, policy, guidance, goals,
objectives, milestones, decisions) for a strategic view of organizational
activity. The app uses the
timevis R package, which is based on
Timeline module and the
htmlwidgets R package. For convenience, I’ve hosted
a demo of stratvis on
my Shiny server, so you can scroll through the interactive
timeline and watch the acronym list adjust automatically.
Relevant background on the timevis API
When a timeline widget is created in a Shiny app with the
timevis method, four Shiny inputs
are also created (and updated as the interactive timeline is manipulated within the app).
The names of the inputs are based upon the name given to the timeline object (with
_window appended). We will use the
objects in our
method to build the reactive acronym list below.
If the interactive timeline object is
timelineGroups (as it
is in the
stratvis demo), then the following input variables are available:
input$timelineGroups_data– will return a data.frame containing the data of the items in the timeline. The input is updated every time an item is modified, added, or removed.
input$timelineGroups_window– will return a 2-element vector containing the minimum and maximum dates currently visible in the timeline. The input is updated every time the viewable window of dates is updated (by zooming or moving the window).
Reactively update acronym list
The block of code in
server.R that generates the reactively updated acronym list:
Obviously, the core functionality is provided by the
method, which makes a reactive version of a function that returns a data
frame (or matrix) to be rendered with the DataTables library.
As mentioned above, the
timelineGroups object is the actual
timevis interactive timeline
object, and the following code ensure that the
acronyms Shiny output is
reactively updated whenever the
input changes (i.e. when the minimum or maximum date in the visible timeline
end variables within the
input are selected and then filtered for only those items visible in the timeline:
The call to
filter accomodates ‘point’ and ‘box’ type objects (
type = 'point' or
type = 'box') that do not have end dates (
end = NA) as well as ‘range’ and ‘background’
type objects (
type = 'range' or
type = 'background'). Note that this approach
would also update the acronym list if an item is added interactively to the timeline.
Each row of the
acronyms data frame is an acronym (
acronym variable) and
the full phrase to which it corresponds (
full variable). The following code uses
grepl to filter
acronyms down to only those items present in the
created above. The regular expression used in the call to
grepl is simply
all of the words (separated by white space) in
data$label pasted together with
“|” characters between them.
If you have any feedback on the above approach or the stratvis app in general, please leave a comment below or use the Tweet button. As with any of my projects, feel free to fork the stratvis repo and submit a pull request if you wish to contribute.