Tableau How to color a chart based on two fields, one continuous and other discreet

Question

I have a data set from Kaggle and here is what it looks like: Now I want to plot a map using Tableau which illustrates the advantage/disadvantage of Republican/Democrat. Just picture this, because I have already had the total votes of each party in every single county, it is easy to compare which party won a county. My idea is depicting this fact: if a county is won by Republican, then it should be in red; if by Democrat, it would be in blue; otherwise it would be white if being won by minor parties (I am not sure whether there was such a case).

Note that if the more overwhelming a party is within a county, the darker should the color be. For example, if a Republican won a county tinily by 0.1%, it should be light red; if a county is won by Democrat with a landslide, say 30%, then it should be deep blue.

My problem now is that with the given data, I have no ideas about how to demonstrate the gap of votes between different parties. I guess I might need to create a calculated field that shows the vote difference with a county. But is it the right solution?

---- EDIT---- I found an example: https://public.tableau.com/profile/clillich.kltv#!/vizhome/ElectionResults_5/Dashboard1, it looks good to me. It is just uncertain what its data source looks like.

Answer 1

The example you have shown is perhaps not related to chart as you want. It shows only one measure. Please proceed like this.

Step-1 Create a calculated field win margin in percent with the following calculation

IF [Won] = TRUE then ([Total Votes] -
{FIXED [State],[County] : MAX(
IF [Won] = FALSE then [Total Votes] END )})/
{FIXED [State],[County] : SUM([Total Votes])}
END

Step-2 Convert it to dimension (by right clicking it).

Step-3 simultaneously create a group on party field as desired.

Step-4 select both fields in dimension pane and create a new hierarchy (party-group first and win margin second). Drag this heirarchy to marks card. Convert both to colors. The following gif may help

I think this serves your purpose. Good luck