I have 1) a spatial file with a "region" field within the country (polygons are mapped out based on coordinates) and average $, and 2) an xlsx file with a "postal codes" field and $ of specific properties.
I would like to create a sheet with two layers of map (also known as dual-axis map) as shown in the photo below.
Essentially, there are two layers in this sheet:
- shaded polygons of "region" field to show the average $ in the region
- the specific $ of properties at different postal codes with colour gradient based on $.
File attached for reference on the 2 layers I'm talking about.
How can I achieve this? Please keep in mind that the data sources are 2 separate ones. Since they are using different hierarchies of geographic info (postal code vs regions), I'm not sure how to blend the data. At the same time, Tableau keeps sending an error message: 'In order to use field from Other Data Source, a relationship needs to be created with planning area.' I am not sure which field to use to create relationship.
Appreciate any help. Thanks!
I think you'll have to join the two data sources instead of blending.
My go-to reference for dual axis mapping is: https://community.tableau.com/s/news/a0A4T000001v7SCUAY/dual-axis-mapping-many-ways
Though if you're using Tableau 2020.4+ the map layering feature is amazing.
-Sarah.
Tableau Research
