3 Replies Latest reply on Aug 3, 2016 5:05 PM by Guy Hoffman

    How to create a dual axis map with custom polygons

    Guy Hoffman

      I have created two files (one in excel and one as .csv) via QGIS that contain custom geocoded polygon data. The files do not contain the same fields as one file has additional data pertinent to the specific polygons in that file.

       

      The first file (excel) containing geocoded data is as follows:

       

       

      When mapped, it appears as follows:

       

      All is well. The second file (.csv) containing geocoded data has many other fields (see snippit below) but it does included the shape ID, path and long/Lat data to allow the custom polygon to be mapped.:

       

      When mapped, it appears as follows:

       

       

      What I am trying to do is have the data in these two files presented on the same map. I have tried both a dual axis map but cannot get it to work. When I try, it looks like this:

       

       

      Even though I have edited the relationships in the .csv file to be mapped to their corresponding field in the excel file (e.g., X and Y are mapped to long and lat) and added in the columns and rows as a dual axis, the map disappears and coordinate data is displayed.

       

      I would be grateful if someone might point me in the right direction.  I have included the Tableau file in case that might make it easier.

        • 1. Re: How to create a dual axis map with custom polygons
          Steve Burger

          Guy,


          Good news, bad news.


          Bad news first:

           

          You aren't going to be able to dual-axis the map the way you intend.

          The fix will take some manual data prep before working in Tableau, but it's not terrible.

           

          I don't recommend the table join that you've done.

           

          Good news:

          You can do it.

           

          Details:

          You will need to Union, not blend and dual axis, the spatial data for the custom polygons. Union ONLY the spatial data describing the polygons. You'll see in the attached excel file that we only have Lat, Long, Play, Point Order and Polygon ID.  Then you will want to blend the associated detail data from another data source.

           

          The geospatial data can be separate tabs in excel, or tables in a database, and then union-ed in Tableau.  Example here:

          firstmapsecondmapunion.jpg

           

          So in summary, multiple polygons will have to be detailed in the same source/table, but differentiated by Polygon ID.  Then you could probably blend in the related data, linked on the Polygon ID field.


          Attached is how I re-worked the geo-spatial data in Excel (FirstMapSecondMap.xls) and a sample workbook with the polygons mapped.  You'll have to data prep the related non-geospatial detail data into it's own source.

           

          I've also included my mapping presentation workbook from TC2015. It steps through points, paths and polygons and what is needed in the data.

           

          If this has helped you, or answered your question, please mark it as such so that others can find it quickly.

           

          Best Regards,

          Steve Burger

          Tableau Online Deployment Advisor

          • 2. Re: How to create a dual axis map with custom polygons
            Guy Hoffman

            Steve,

             

            Thanks so much. I will give it a try next week and report my progress.

             

            GH

             

            Sent from my iPhone

            • 3. Re: How to create a dual axis map with custom polygons
              Guy Hoffman

              Steve,

               

              This indeed worked for me. Thanks so much for looking through this.