3 Replies Latest reply on Feb 11, 2016 2:03 PM by Evan MacDougall

    How do I Calculate Medians with Custom Polygon Maps?

    Evan MacDougall

      I have imported a custom polygon layer that I have created that shows proprietary submarket boundaries for each of our markets.  Each market has a unique identifier (DIV_ID), and each submarket has a both a unique identifier within each market (SUB_ID) and overall (DIVSUB_ID).  This layer displays just fine using the standard instructions from bringing in polygons from ESRI into Tableau.


      I have another table that has individual home closings.  There are about 40 columns of data in this table, including a DIV_ID, SUB_ID, and DIVSUB_ID.  All records have correct values for each of these columns, and they match up to the corresponding fields in the polygon layer.


      I can easily link the polygon layer and the table of home closings using the DIVSUB_ID columns.  I can color the polygons by all kinds of measures., but I am unable to color my polygons using medians.


      I have a SalePrice column in my home closings table.  Every record has a value, tho, some of them are zero.  SalePrice is a number.  It's a measure.  And I've defined it as continuous.  I can color the map using the SalePrice measure using just about any of the available calculations (SUM, AVERAGE, COUNT, STD DEV, Minimum, Maximum, etc). However, it will NOT color my map using the MEDIAN SalePrice.  When I choose Median, the SalePrice color turns red and my map will grey out and not display.


      I've tried creating a filter and only allowing a range of values so that I don't include any values lower than 1 or and null values.  But, that hasn't helped at all.


      What am I doing wrong?  Or is this a Tableau custom polygon map issue?  I've done a quick scan of the forum and Tableau help files and found nothing about this. If it's not something I'm doing wrong I would expect other people to be asking about this.  Anyone have any suggestions?


      I can always calculate the medians in Excel and then color my map using those values, but then the values aren't dynamic.  I want to be able to quickly have the map re-colored if I decide to filter for home type, new/resale, etc.  So, bringing in static values is not the solution I'm looking for.