3 Replies Latest reply on Jan 23, 2009 11:40 AM by Alex Blakemore

    date annotations - ghant charts with multiple dates per bar - or other more complex time series data

    Alex Blakemore

      Here's a situation that arises frequently that I'm not sure how to best show in Tableau, but could probably use a new feature -- maybe a new kind of annotation.


      I want to show progress for various tasks over time. Usually, I use a continuous time field [Start Date] on the columns shelf, and a discrete field [Task name] on the rows shelf. I can then make a ghant bar chart, with the size shelf showing [Task Duration (days)]. This is similar to Date & Time Sample workbook, lesson 7.

      A task can repeat periodically, two instances can overlap (thanks for the transparency slider). All is well, EXCEPT ...


      Often a task has multiple dates associated with it: such as an [Approval Date], [Planned Completion Date], [Actual Completion Date], [Code Review Date], [Test Passed Date] etc.


      I'd like to have some sort of visualization, probably similar to ghant charts, that let readers see at a glance, the tasks, and status of the various dates for each. I could use a reference line to show some global deadline that applied to all tasks, but not to mark each bar with its various dates.


      Making a long series of the same charts, each of which shows one of the relevant dates is painful, and not very useful to the reader.


      What might work would be the ability to add annotations that showed the other dates for each bar, but instead of displaying the annotations as text, would put an icon or a line at the appropriate place in the ghant bar, maybe with a label, or color.


      Think of horizontal ghant bars for each order which start at the time of order creation and end at delivery, but have small markers on each bar to show when the order was sent to the warehouse and when it was shipped to the customer. It would be good to be able to control the annotation format to say show [Deadline Date] as a red bar say - or even better, have some dynamic control so [Ship Date] is bold if its > 2 days after [Order Date]


      Or maybe add a second field to the row shelf with the [Task Phase] would work for some of these.


      Any ideas on how to do this with the current Tableau or another vis that accomplishes the same goal? If not, please consider something like this for a new version of Tableau. In a nutshell, there needs to be a better way to see detailed timelines.

        • 1. Re: date annotations - ghant charts with multiple dates per bar - or other more complex time series data
          Jeff Mills

          Hey Alex,

          I think I understand what you are asking for.  There is a way that we can do this and it uses the level of detail shelf.


          First you want to create a calculation that returns the difference between the start and the end of a project.  Similar to this:

          DATEDIFF('day',[Order Date],[Ship Date] )


          You will use your current chart type of a horizontal Gantt bar.  You will place this duration calculation on size.  Remember to turn your date dimension to continuous and chose all values.


          The level of detail shelf is where you will put your intermediary dates.  Be sure that these are also continous and set to all values.


          The last step is to format the marks by turning borders on.  This will now show you the lines at each phase in the process.


          I have attached a workbook using a sample data set that helps illustrate this point.


          Hopefully this is of some help. 


          ~Jeff Mills, Tableau Software.

          • 2. Re: date annotations - ghant charts with multiple dates per bar - or other more complex time series data
            Michael Cristiani

            Hello, Alex and Jeff.


            After looking at Jeff's workbook, I started thinking (bad policy).  The result is the attached, revised version of your workbook, Jeff.  The main items of interest are:


            Your viz begged the question for me if there were overlapping marks, and what does this mean for Alex's objectives.  In the attached, see the the sheet, "Are There Overlaps?".  There are clearly overlapping marks.


            So then the question is, "Why?"  One reason might be the Ship mode is obscured.  See the sheet, "Step 1: Add Ship Mode to Color Shelf".  It adds Ship Mode to the Color Shelf, and uses the transparency slider to explore potential overlaps and tease out the Ship Mode.


            This leads to the next question, whether Order ID can shed more light on the overlaps matter.  Sure enough, take a look at sheet, "Step 2: Add Order ID to Row Shelf". 


            And because there are now still overlaps, adding Ship Mode also to the Row Shelf ("Step 3: Add Ship Mode to Row Shelf") reveals that indeed some orders have multiple Ship Modes, effecting the Days to Ship.


            Getting back to Alex's thinking about the viz, can the concept of met/blew a deadline be incorporated here.  See sheet, "Step 4:  Expand Ship Mode Indicator to Include Deadline Evaluation", for the obvious answer, based on Alex's criterion.  Shades of the same color within Ship Mode to indicate whether a deadline was met.


            Step 5 , Step 6, and Step 7, apply this approach to the original Sheet1 viz in Jeff's workbook.


            Any thoughts?  Does this approach help, Alex?


            MANY BLESSINGS!

            Peace and All Good!


            Michael W Cristiani


            Voice:  513-333-0710

            e-mail:  mike@migsite.com

            • 3. Re: date annotations - ghant charts with multiple dates per bar - or other more complex time series data
              Alex Blakemore

              Michael et al,


              Thanks for the nice workbook with timelines. It goes part of the way towards what I'm asking for.


              But I think Tableau could still use some new features (I suggest with datetime annotations, but perhaps in some other way) to be better able to show detailed timeline data.


              Especially when showing both time "intervals" (e.g. ghant bars showing tasks with durations) and time "instants" (points in time, e.g. deadlines), and also phase transitions (task goes through multiple phases before completing)


              I tried to illustrate a bit in the attached workbook.

              Note how poorly text annotations work as a way to show deadlines on the first worksheet.


              P.S. One trick I noticed after first posting this is that you can approximate a point marker by making a mark annotation with no text and no line, just an arrowhead (and then positioning the arrowhead).


              One reason that doesn't work well is that its difficult to position the arrowhead exactly, you can't change the arrowhead icon beyond a few simple choices or color, and most importantly the position of the arrowhead is not drawn from the data, but is positioned by hand. That obviously doesn't scale up.