Today we are going see use of polygon and points in Tableau to create an map showing an geographical details. Tableau has out of the box visualization of geographic regions such as countries, zip code, states and it is pretty much simple by simple drag and drop into sheet with geocoding fields in data source.
Now, what if we need to see customize location in the map or geographical boundaries across across different suburbs or need to see municipal map of particular city with different sub-wards. Tableau for that purpose has polygons which can be used for drawing an particular spot but this required a bit of work before we start using it. This collecting of data with all the points might be time consuming process.
Lets get started with this:
Custom polygon has 2 requirements:
1 – Latitude and longitude coordinates for each point of polygon
2 – An point order in which points are connected with each other
For this dashboard, we will create Mumbai map on basis of municipality wards and I found that data from json file here and converted that into an excel spreadsheet. Once you have data arranged in below format, Tableau will connect the points with the help of longitude and latitude information:
once your data is ready with wards,points, longitude and latitude then import the data into Tableau then do following steps:
- Place longitude and latitude on rows and columns respectively
- change mark type to polygon
- Convert points into dimension then place points column into path under mark
- Final step is to place ward column into colours under mark
Your polygon map is ready for Mumbai with different Ward with its boundaries as shown below:
Next I did was to get 2011 census data of Mumbai population and create different sheets to create dashboard which shows population, literacy and working class for each ward.
Here is the final dashboard that I designed and published:
Do let me know your feedback or if you have any queries on the same.