Clustering markers with exceptions (Google maps android API) - javascript

Iam looking for a way to cluster all my markers on google maps except of a few markers. These few markers may vary from time to time. Means for example: All markers contain an information like a number for instance. If the user watches the map of Europe all markers shall be clustered except of those 3 markers with the highest number. If the user moves to North America on the map or zooms out to see the whole world, all markers shall again/still be clustered except of the 3 markers containing the highest number. These 3 markers could now of course be different markers.
Any idea where and how to start is warmly appreciated. Is it even possible?

Yes, its possible.
For a marker to be clusterizable you have to explicitly add it to a ClusterManager doing mClusterManager.addItem(myClusterizableItem); (See the documentation).
So, you only need to add all the markers to the ClusterManager and create some markers (the ones you don't want to cluster) the usual way using the mMap.addMarker method.
Another way could be to write a custom ClusterRenderer that clusters your markers based on some conditions and exclude the markers you don't want to cluster.

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how to display moving points on a map from a database

There are logs where it is indicated: board number, time, date, latitude and longitude. information about their movement is constantly updated and new boards appear. how to display their movement on the map?
To display markers on a map, you can perhaps use Leafletjs for Javascript.
It is useful library that allows you to use a large array of mapping basemaps, and plot overlays on it, such as adding markers based on latitude or longitude, or drawing polygons or shapes. You can also overlay multiple maps, and there is a lot of functionality linked to the elements.
See their tutorials to get started or reference the documentation to see how you can manipulate the markers on a map.

how to highlight a state in google maps on click any area in the state of a country

I am willing to highlight a state in the Google maps when user click on any area in the particular state. Supprose if I click on any area in the Washington sate. Then the Washington should be highlighted. Can you help me if any api or js is available to do like that.
There is no automatic API for this. You are going to have to draw a polygon either dynamically when the user clicks, or pre-draw all the U.S. State polygons in advance and hidden, then dynamically make the proper one visible when the user clicks.
As for making polygons in the shape of at least U.S. states, several persons have posted pre-defined polygon lists. One is here in StackOverflow: Geographical boundaries of states/provinces -> Google Maps Polygon
However, if you are looking at world-wide regions, states, and provinces, I doubt you will find pre-defined lists of them all. You may well have to create your own polygons by manually drawing on a Google Map or Google Earth, then export the polygon's lat/lng waypoints.
recently I am creating some relative, the tests I made was based on OpenStreetMap Nominatim (https://wiki.openstreetmap.org/wiki/Nominatim), is something like:
Click on map get Lat, Lng
Search by reverse Geocode, get state (or city)
Use Nominatim API to get a polygon_text (I use the geo WKT format), parse it
Draw the polygon or polygons (if multiplygon) with Google Maps API
Hope it could make some ideas come.

How to deal with multiple Google Maps markers on the exact same position

What I'm trying to do is finding an elegant way of dealing with multiple markers on the exact same spot on a google map. Possible scenarios are when your geo data just isn't accurate enough to distinguish two markers from one another (say 3 people live in the same house and all you have is an address) or you only have city information of a couple of shops.
Now there is the Clusterer of course, everybody is saying that, but that won't help here as the markers have the exact same location. They will stay clustered regardless of zoom level.
I like the way Google Earth does it. Here is an example. But so far I have not discovered a way to have this behavior in Google Maps. I would be pleased if someone can show me how to do this.
So perhaps as you are looping through your coordinates adding all the markers, you could check if any previous marker has the same latlng. If it has you could use a different marker, e.g one numbered '2'. Or to do the Google Earth thing, offset each marker slightly, and draw a polyline from the markers to the original location.

Spreading markers out as necessary in Google Maps

I'm displaying many (hundreds) of markers at a time in a given viewport in Google Maps. Often, this leads to markers being drawn over each other.
Since the exact positions aren't as important at zoom levels where so many markers are drawn, is there a library or piece of code that allows markers to dynamically update their position based on whether they are overlapping with other markers or not? As the user zooms in (and markers becomes more sparse), the markers will then move closer to their real positions.
And yes, I know about groupings, marker clusterings, etc. Those solutions aren't appropriate in my situation, since it is important that all markers be displayed at all times. And in actuality, I am already using those techniques as well, where appropriate. I'm using the Javascript V3 API.
You probably need to implement your own clustering algorithm - I think Google Maps let's you implement your own strategy (I know Bing Maps does, and typical they copy each other within 6 months or so of a new feature being implemented).
Note that for lots of dense pushpins, your constrains of separation but displaying all pins, are in conflict.
as for a strategy, my first thought is an annealing type of algorithm, although it probably isn't very fast. Basically each pushpin would exert a force on surrounding pushpins within a certain distance. iterate until sufficiently stable.

Google Maps API V3 - Load map first and then load markers

I am creating a page to show a list of locations(markers) on Google maps. The number of markers is dynamic and can be quite large. This will adversely affect user experience when the map (along with the markers) are taking too long to load.
Can anyone point me in the right direction to load the map first and then load the markers. Any help much appreciated.
Use a marker manager. I used one for Google Maps API v2 (for on-demand loading of ~2000 markers via AJAX) and I am sure there's one for API v3. A marker manager is class that allows you to selectively display markers on a Google Map. Instead of adding markers to map, you use add them to the marker manager and it takes care of when and how to display the markers. The markers that lie outside the "visible" region are removed hence its fairly memory efficient. A marker manager class may provide "clustering" option (or may be you need another class for this). A cluster manager displays one marker that encompasses multiple markers when markers are too close, specially at high zoom level. Hope this helps you in the right direction.

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