Filled maps aren't that great for this sort of thing for three reasons: Primarily that because the size of zip codes varies so it can look like candidate A got way more votes than candidate B (take a look at any US red/blue election map by state and you'll see this problem). Secondarily because that would require some set of decisions to split each zip code and that gets really messy really quickly (and exacerbates the problems with zip code size). Thirdly is particular to zip codes, some zip codes such as military zip codes for APO/FPO have a physical location but no area.
The most commonly used alternative for displaying proportions of multiple discrete elements in a map is a pie chart, like this where I used two Departments from Superstore Sales to create the two colors on Manhattan, and used a secondary axis filled map to highlight the zip codes where there's data. Note the cluster of pies in the middle where there are zip codes with no area:
v9.3 workbook is attached.
pie chart on map.twbx 1.3 MB
I am also new for Tableau and want to achieve same result (filled map with pie) , but my data looks something like this -
County State Student typeA Student typeB Student typeC Essex New Jersey 50 10 9 Fairfield Connecticut 18 1 5 New York New York 158 40 30 Bergen New Jersey 80 60 40 Queens New York 86 44 22
I truly appreciate a help on this.