When using Tableau's native geometries and generated latitudes & longitudes, maps show marks for every geometry (state, county, or zip) on both axis. Many times users want to show all marks on one axis, but only selected marks on the other axis -- for instance showing non-null values. But if a filter is applied to eliminate the nulls the marks on the other axis are also eliminated. While we can't use filters to eliminated the dots, we can hide them by using a "blank" shape.
Here is a ZIP Code map that demonstrates the issue:
You can use a blank shape to fix this problem:
What is a blank shape? It's a png that contains only the alpha channel, nothing else (see attached). This produces a completely transparent shape
Here are the steps needed to create this viz:
- In Windows explorer create a new folder in your Shape folder named "Blank Shape" (e.g. D:\Shawn\My Tableau Repository\Shapes\Blank Shape)
- Download Blank Shape.png and put it in your Blank Shape folder
- Create a dual axis map with a filled map on one axis and a shape on the other axis
- Create a calculated field that differentiate what you want to show and what you want to hide.
- Go to Edit Shapes. Click the shape you want to hide. Open the Blank Shape palette.
- Even though it looks blank, there really is a shape there. Move your mouse in the upper left corner to see it:
If you don't see the Blank Shape Palette you may have to click Reload Shapes.
This idea is from a workbook Jonathan Drummey sent to me. I think it is a much better way of doing this than trying to sync up colors and hiding them against the background. (Thanks Jonathan!)