At the moment I have a web app that uses Google Maps APIs to get distance between one location (store) and a list of other locations (techs), as its all cached in a DB, it only has to run once. But its very slow that first time....
What im needing to do now is make a front end for customers, where they can enter in their address and find the closest store. As there is a tone of stores, trying to get addresses of each store and comparing it with the customers address using Google Maps API is going to take forever.
So what techniques are available to make this faster? Is it possible to filter out most of the addresses with the difference of lat and long? Or is their an API method that I can give Google Maps with a long list of addresses and have it return the closest address?
What you're supposed to do is when adding the stores to the database also include their lat/lngs. This way when the user enters their address, you just need to geocode their address(get the lat/lng), and use the haversine formula (which is just math so it runs fast) to get the closest locations.
https://developers.google.com/maps/articles/phpsqlsearch_v3
You can use the google geocoding api to get/insert the lat/lng of the stores already in your database.
I currently have a locator that searches tens of thousands of stores and it executes in under a second using this method.
Unfortunately there isn't such a function in Google maps API and you have to implement it yourself. A good start is the mysql point data type to store the locations geo location and a spatial index. A spatial index reduces the dimension complexity and makes nearest-neighbor lookup simple. A spatial index is a r-tree and a space filling curve, for example a hilbert curve. Here is a nice article about hilbert curves: http://blog.notdot.net/2009/11/Damn-Cool-Algorithms-Spatial-indexing-with-Quadtrees-and-Hilbert-Curves. Here is an example of a spatial index with mysql: Selecting nearest geo coordinates using spatial index on mysql table not working. Here is an example of mysql distance function Correct way of finding distance between two coordinates using spatial function in MySql. Here is an example of MySql 5.1 http://www.elevatedcode.com/articles/2009/03/06/speeding-up-location-based-searches/.
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I've got a list of shops that I have put in a javascript array. I have their addresses as well.
I'm needing to create an autocomplete which allows me to put in a city name and it displays the 3 nearest to that location. I imagine it will need to interface with google's apis some how but not sure where to start.
I've got the actual autocomplete jquery stuff working on an ajax script, but I don't know how to get things located nearest.
You need the lat/long locations of the stores, https://developers.google.com/maps/documentation/geocoding/ Then you need the lat/long location of the user, with some relatively simple mathematics you can then calculate the distance between these two points:
$distance = round((6371*3.1415926*sqrt(($lat2-$lat1)*($lat2-$lat1) +
cos($lat2/57.29578)*cos($lat1/57.29578)*($lon2-$lon1)*($lon2-$lon1))/180), 1);
If you have a large number of stores and a large number of users I advise caching these distances in a mysql table, you have to do this for each store in your database. So you create a table for each e.g. zipcode that requests this and put up a cron to remove these tables every hour or so.
So the process:
User asks for the nearest store
You get his location through google api (or your own storage)
Check if there's a table for his location
If yes, give him the results directly, if no generate the table and give him the results
Mind that google only allows a limited number of data requests. Even though this number is huge (I believe 25.000 requests per day) it may be advisable to store the lat-lon locations of your stores AND users. Would also improve the speed.
I made something similar to this, I fetched the lat/lon locations at the moment a location was inserted into the database and inserted it in a seperate per-zipcode lat/lon table.
Let's say your site has 200,000 unique users a day. So, your server is heavily loaded/pounded; and you do NOT have resources to buy a bigger/better server. So, you are stuck with what you have.
Now, whenever a user comes to your site, you need to do some calculation (calculate distance between user city as detected via GeoIP and some whitelist of cities, figure out the nearest city within 140 mile radius).
Would you do this calculation via PHP or via JavaScript?
First, would you precalculate all nearby cities within 140 mile radius of whitelisted cities? For eg: Whitelist city 1 can have 20 nearby cities. Or would you do on-the-fly calculation everytime?
For eg:
Whitelist = Detroit, MI
and nearby city = Kalamazoo, MI (140 miles)
Second, if pre-computed: would you store this in XML file or some MySQL table? Now, we just have to search through a table (mysql or xml no more than 1 mb in size). I am guessing this would be inefficient because client browser (JavaScript) would have to download 1mb xml and search through it. This would make page load time even slower. Using DB might be faster but then DB load increases (if 200,000 unique users are trying to load the page over the course of a day).
Maybe the best way to do would be to do precompute, store precomputed results in XML, and then use PHP to search through XML and find nearest whitelisted city to user?
If you, the site, are actually relying on the city information, then you must do the calculation on the server.
Database queries are almost always going to be faster than XML searches for sufficiently large XML files. You can optimize the query, MySQL will cache things, etc.
Pre-calculating all city-city distances would be a way to go, for sure. GeoIP doesn't only provide city names, it does give actual latitude/longitude locations as well. I'm sure that the possible list of cities changes rather constantly, too.
I would look into using the geospacial capabilities of MySQL. General over view of searching by coordinates here:
Fastest Way to Find Distance Between Two Lat/Long Points
In short what you will do is setup a database of the cities you care about, with their lat/long, and query that table based on the GeoIP provided lat/long.
So, I am trying to develop an application that will display user listings. The site should detect user location (I am using maxmind api for that) and then show listsings from user's location + cities within a user-specified radius.
How do I do this? MaxMind API lets me detect user's city by IP address but how do I find nearby cities?
Reference site: www.oodle.com (you can also manually change city+radius).
Sanguine
Rather than store and compare cities, store and compare latitudes and longitudes, which are concrete locations rather than ambiguous names. All of MaxMind's GeoIP databases provide them. A quick Google search should provide you the math to calculate distances between points on the earth.
If you actually want to find nearby cities, not nearby users as you've said, then you need a database mapping cities to locations. Again, MaxMind provides this with all their databases. Go to their website, go to the page about the database you purchased or downloaded, and look at the instructions for inserting the CSV format into a SQL database. That'll get you the latitude and longitude of each city. Then, again, a Google search will provide you the math to calculate the distance between two points on the earth (lat/long pairs) in a SQL query. Order by that calculation to get the nearest cities.
Sorry to give you only advice rather than code, but there's a lot of little things you've just gotta do yourself to build this site.
I have a MySQL database of addresses (my custom points of interest - not Googles) and their associated Lat/Long. What would be the simplest way for a user to my site (their lat/long is also stored in their user profile) to be shown a:
google map with their own lat/long as a starting (center) point
default radius of 10 Miles
all Points of Interest within that 10mile radius
If it is simpler to use zipcodes for the POI's and the user I have those as well.
Thanks in advance for any advice given, or information leading to tutorials that could get this done.
You can see how to get the lat/lon radius on another question: php mysql compare long and lat, return ones under 10 miles
You will need to implement access to the google maps api and dump the variables into the points of interest. You may be able to glean some useful information from a cakephp helper:
http://github.com/cdburgess/helpers/blob/master/google_map.php
You should be able to strip out the function and use it properly in PHP.
I'm developing a store location application.
Looking up a store, it currently shows the location in googlemaps based on address and zip code.
Now I want to build a function which also shows other shops within 500 meter radius.
To do this, I have to do a proximity search / calculation.
My biggest question, is how I should approach this.
I did find this link, which has some example code. But I'm unsure if I can use the code (and which of the codes I should use). Does anyone have better examples?
Also I'm thinking of adding a new table to the database, which stores the geo code for each store. Do I need more fields than 'id', 'latitude' and 'longitude' ?
UPDATE
I just found this link at phpro.org. It looks like it's just what I need! Has anyone used their examples and can comment upon it?
You cant radius search directly with the google maps API, however, you should know (or can figure them out via geocoding their addresses) the latitude and longitude of each point of interest (POI) you want to include in the search.
After this you can use the Great Circle equation to search for proximity, and it turns out to be very fast. We have implemented this as a stored procedure for the locator service at my work and use it to search through >3500 locations with response times under 0.1 seconds.
Some SQL implementations contain geospatial extensions. In those implementations you can directly write a WHERE clause that filters the results by distance from a specified point.
Check the documentation of your SQL implementation. If it has geospatial POINT type, then it makes sense to enter the coordinates as POINTs rather than a lat/lng pair, and consider using that field as a SPATIAL KEY if you're going to be accessing the table mainly by location.