11 Replies Latest reply on Mar 11, 2012 1:03 PM by Kirdan Lees

    help with interactive map and bar chart

    Kirdan Lees

      I'm exploring visualising some migration data from New Zealand. Each data point represents an individual, moving into a particular region (Canterbury). Each data row contains the exact date, the postcode (about 1000) and region (about 18). There are roughly 8,000 rows in total.


      My first take on this was to use dots on the map to build up, over time, a picture of the postcodes individuals haved move from.

      Alongside this I wanted to have a barchart that updates counts of each region over time.


      I used dates as pages to bring up the dots over time. I'd like to make the pages field global, (I guess) for the barchart but I can't seem to get this to fly. Is there a knack to setting this up? Love to hear thoughts about how else I could represent the data.


      I'm also worried about how to treat the dots that overlap on the same point for each suburb.As far as I can make out each dot represents anywhere between 1 and 6 individuals. I can use colour but not sure that this represents the migration that well.


      Any comments, both on the technical aspect and on different takes on how to display the data, most welcome.





        • 1. Re: help with interactive map and bar chart
          Shawn Wallwork

          Hi Kirdan, you're going to need to export a packaged workbook, for us to be able to take a look. (It'll be a .twbx instead of a .twb)



          • 2. Re: help with interactive map and bar chart
            Kirdan Lees

            Hi Shawn,


            Thanks for the heads up and apologies for not posting the twbx file.

            I've attached this now.

            Love to know what you think,




            • 3. Re: help with interactive map and bar chart
              Richard Leeke

              As a fellow New Zealander I couldn't resist having a go at this.


              I've done a few things to help with the mechanics - other people may have more suggestions on the most effective way to present it.


              Getting the pages shelf to coordinate between the two sheets on the dashboard was just a matter of setting both to use the same time granularity - you had day for one and year for the other. I set them both to month (I was getting bored watching the paint dry with it set to day - even on the fastest setting).


              I've changed both the bar chart and the colour of the dots on the map to be running sums, rather than just counts). That way you build up the cumulative picture. I also duplicated the running count of postcode from colour to size to emphasis the hotspots in the source of migration. That one in Blenheim, and to a lesser extent Nelson are suprising - is this real data?


              I experimented with colouring the map by region. I tried a dual-axis map with a filled map coloured by region with your postcode dots overlaid - but the regional colouring tended to mask the dots. I also tried colouring the dots by region and relying on size for the number of migrants - but eventually decided that there was no need - the position of the dots on the map and the bar chart already convey that information twice - no need for a third way.


              I also fiddled with the size scale settings a bit - otherwise the dots for single migrants from a postcode barely showed.

              • 4. Re: help with interactive map and bar chart
                Shawn Wallwork

                Kirdan, I started with Richard's version and added a few tweaks. Not being a fellow New Zealander, I was curious where these regions were, so I used color on both the bar chart and map to show this. I also added a reference line to the bar chart, as well as highlight actions to everything. And tweaked the layout a bit. BTW, interesting information. Here's what it looks like:




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                • 5. Re: help with interactive map and bar chart
                  Kirdan Lees

                  Hi Richard,


                  Love your work! And loved your other viz on the quakes from early last year too.


                  I understand this much more now and I like where I can go with the data.


                  It is live data but migration into the region so will need to check out the Blenheim/Nelson data like you suggest.


                  Will do something with the more interesting out migration when i get this up and running.


                  Unfortunately I'm struggling with the last piece of the puzzle I still don't understand.


                  When I open your workbook, there is that pesky red exclamation mark in the taxpayer count field. When I change this to month, not too much of a  problem. I get a nice looking viz that cranks through the map but the barchart updates by giving counts by month rather than cumulative sum across months. Ok, so I change the field to a quick table calculation calcuated field, running total, compute using date applied (or previous region field) and then no result.

                  I can get cumulation across each year and then the region total reset at the start of 2011. Frustrating, particularly when I reset the "starting every" field to none.


                  Does this seem strange to you? Same problem when I open Shawn's viz too.


                  Am running desktop on a 64-bit dell.


                  But thanks heaps for the help, just trying to get that last tweak sorted.




                  • 6. Re: help with interactive map and bar chart
                    Kirdan Lees

                    Hey there Shawn,


                    That was some nice work putting that together. Put me to shame! The colour is pretty effective and highlighting the regions works really well. I'm very impressed!


                    Unfortunately I'm still struggling with the last tweak to make everything come together.

                    As I explain to Richard above, I can't seem to get the summation to run across years. And I get that red exclamation mark when I open your viz which of course makes me suspicous. I've tried to start from scratch and build up but can't seem to recreate the summation running across the years.


                    Any quick thoughts appreciated but I can see you've spent some time on this already.

                    Where do you work out of?


                    Thanks heaps for the input to date,



                    • 7. Re: help with interactive map and bar chart
                      Richard Leeke

                      Hmmm - I don't see the pesky red exclamation mark on mine, yours or Shawn's.


                      About the only thing I can think of is that you are on 7.0.0, whereas Shawn and I are on 7.0.1 (I can see that by peeking at the XML of the workbooks). I wasn't aware of any issues in that space - but maybe this is a case where a workbook created with 7.0.1 doesn't work with 7.0.0.


                      It's probably worth trying upgrading. 7.0.1 seems pretty stable - I had one crash almost as soon as I installed it, which Tableau support say a few people have hit, but it's been solid since then.


                      I'm not quite sure I follow what you are trying to do with the running sum by year. I initially interpreted that as a side-effect of the calculation being broken - but having just read your comment to Shawn I'm not so sure.


                      Maybe try 7.0.1 and let us know if that fixed the red exclamation mark - and also if you're still having an issue with the running sum maybe post some screenshots showing what's happening.

                      1 of 1 people found this helpful
                      • 8. Re: help with interactive map and bar chart
                        Kirdan Lees

                        Wow - reinstalled, well installed 7.0.1 and no problems at all now.

                        I had a look at the list of bugs for 7.0 and no warning lights come up so not sure what was going on.


                        And makes me appreciate the value in what you and Shawn put together!

                        Will now put together the out-migration version.


                        Thanks for all the help!



                        • 9. Re: help with interactive map and bar chart
                          Richard Leeke

                          Glad that 7.0.1 fixed your pesky red exclamation mark. That's interesting, though, I don't ever recall seeing incompatibilities between workbooks created with different minor releases like that before.

                          • 10. Re: help with interactive map and bar chart
                            Shawn Wallwork

                            Where do you work out of?

                            Kirdan, Placitas (near Santa Fe) NM, USA. I do data viz consulting for my wife's advertising agency. How about you? What industry/job do you use Tableau for?



                            • 11. Re: help with interactive map and bar chart
                              Kirdan Lees

                              Hi Shawn,


                              Sorry, I"m an economist at NZIER, a consultancy in Wellington.

                              My skill base isn't Tableau but it's a powerful tool to communicate and let others explore key messages.


                              Thanks again for your help with the migration viz,