Another way of working on this could be via a Data Prep solution that can extract data from web pages (seeing as we are looking to the web for data) and address the problem of manually creating the Excel spreadsheet.
For starters, from this URL - https://en.wikipedia.org/wiki/Political_groups_of_the_European_Parliament , I just did a Ctrl-A to copy the entire page, and dragged everything into Datawatch Monarch, a data prep solution that has partnered with Tableau.
Monarch automatically detects the tables in the page and you may choose what to load - in this case I just picked the tables for the 6th to 8th European Parliaments. From there you can do various data prep functions. For the tables for the 6th to 7th parliaments, I added a column for the parliament num, did a replace on the blank values, and appended the tables to produce a single table showing the composition of each Parliament (group, sub-parties, leader, est, seats by member state).
These are just samples of what you can do. To grow your data set, you can drag in other web pages (or other data sources), and combine that with the existing table/s. Once you have the data set you want, you could then export to a TDE file (instead of xls) for you to create your visualizations in Tableau.
For your reference, Monarch may be downloaded here: http://www.datawatch.com/monarch-free-offer/
An example of how Monarch does web scraping may be found here: https://community.datawatch.com/videos/1702
Datawatch is an official partner of Tableau Software.
Hope this helps further.
EU political parties.xlsx 9.6 KB
thanks for your reply. The tool sounds useful, however, I am a Mac user and that was a game stopper for me..