Update 2: This is announced as fixed in Tableau Desktop 8.2.2 but not in server
http://vizdiff.blogspot.com/2014/08/tableau-bug-fix-color-palette-range.html

Update 1: After communicating with Tableau support staff, the question came down to: whose color range definition to respect? The user's or the data source range?

In the absence of color range definition, Tableau uses the data source's lowest-highest values to set color range. That's totally fine.

However, when the user has defined the color range, Tableau has no excuse but to follow the user's definition.

For example, the user defines the color range to be 1-100. Even if the the data source has a range of 10-20 or -100 to +200, you just can't use those as the color range. You have to respect what the user defines. He means it.

In my case, I defined 2 of the 3 control points of the color range. I want them to be respected. Tableau can't alter it by saying that the data source only contains zeros. My definition must have priority over the data range.

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In a heat map, I need to assign red color to value 0 and green to all values above 0. Currently all the data are made 0 just for showing what the problem is. I am using Tableau 8.1.6.

The Red-Green Diverging Palette is selected. The way I define the color range is Start==0, Center==1, and leave End open. To my surprise, the color range is made to be 0-0 as we can see a 0 is automatically placed in End box by default. The Center value is totally ignored. And I get all my values to be green. Changing Center value to higher value doesn't have any effect. The total palette remains green. From 0-1, the color is supposed to be red but it is not working.

Tableau customer support staff replied that the upper limit is detected automatically in case it is left open. It seems the detection algorithm is to pick the lower limit rather than the center value. This logic surprises me very much.



If I give a fixed number to End, then it works. But, in most cases, I don't know what the highest value is for End. And it's an option to not give one.


A fix would be to simply make the color range to be Start-Center if no value is larger than Center.
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