Automatically apply a map filter using a URL or Query String

Thanks for your help.

I have tried that and it works for a single filter. But once I have done that I can’t use the filters on the map on the front end.

To give you more context…

My setup:
– I have a Mashup map displaying all ‘location’ posts (custom posts)
– I have a ‘location_type’ custom taxonomy set on ‘location’ posts
– My map has a filter setup in the MapPress plugin settings using location_types as check boxes
– I can filter the locations posts using the map filter UI on the location_types – this is all working really well

What I’d like to do is:
– apply a filter to the map from the URL
– see the filter appplied to the map on the filter UI
– change the map filter using the filter UI to a different filter

This is where I am at:

I am using a URL /map/?location_type=cafe-shop

my PHP is

if ( get_query_var('location_type') ) {
	$filter = get_query_var('location_type');			
	echo do_shortcode('[mashup query="post_type=location&location_type=' . $filter. '"]'); 
}

The map filters by ‘cafe-shop’ as expected.

Issues:
– The filter list on the UI does not have ‘cafe-shop’ selected
– If I try to change the filter to something else usising the UI, the filter does not work, it stays on ‘cafe-shop’

Is there a way of pre-filtering the map and then allowing the user to interact with the filters?

Thanks