Hi there,

by default, no, there isn't a way to enable visitors to be able to filter the map by groups or cities.

One very simply idea to enable filtering by groups, is to create multiple pages, one for each group, and put blocks on each filtered to each group. Then you'd put an auto-nav block above each block for quick navigation between the pages. This has the _effect_ of filtering by groups, but it's really just someone visiting different pages.

That being said, I have for some clients implemented some javascript filters on the page, by creating custom block templates. If you are a developer you might be able to investigate that, otherwise you're welcome to email me at ryan@mesuva.co.uk with more details as to what you are wanting to do (if you have a link to an existing map that would be great too), and I can then get back to you with a costing to implement.

Cheers
-Ryan