Shallow Thoughts : tags : geolocation

Akkana's Musings on Open Source Computing, Science, and Nature.

Tue, 20 Aug 2013

Using Google Maps with Python to turn a list of addresses into waypoints

A few days ago I tlaked about how I use making waypoint files for a list of house addresses is OsmAnd. For waypoint files, you need latitude/longitude coordinates, and I was getting those from a web page that used the online Google Maps API to convert an address into latitude and longitude coordinates.

It was pretty cool at first, but pasting every address into the latitude/longitude web page and then pasting the resulting coordinates into the address file, got old, fast. That's exactly the sort of repetitive task that computers are supposed to handle for us.

The lat/lon page used Javascript and the Google Maps API. and I already had a Google Maps API key (they have all sorts of fun APIs for map geeks) ... but I really wanted something that could run locally, reading and converting a local file.

And then I discovered the Python googlemaps package. Exactly what I needed! It's in the Python Package Index, so I installed it with pip install googlemaps. That enabled me to change my waymaker Python script: if the first line of a description wasn't a latitude and longitude, instead it looked for something that might be an address.

Addresses in my data files might be one line or might be two, but since they're all US addresses, I know they'll end with a two-capital-letter state abbreviation and a 5-digit zip code: 2948 W Main St. Anytown, NM 12345. You can find that with a regular expression:

    match = re.search('.*[A-Z]{2}\s+\d{5}$', line)

But first I needed to check whether the first line of the entry was already latitude/longitude coordinates, since I'd already converted some of my files. That uses another regular expression. Python doesn't seem to have a built-in way to search for generic numeric expressions (containing digits, decimal points or +/- symbols) so I made one, since I had to use it twice if I was searching for two numbers with whitespace between them.

    numeric = '[\+\-\d\.]'
    match = re.search('^(%s+)\s+(%s+)$' % (numeric, numeric),
                      line)
(For anyone who wants to quibble, I know the regular expression isn't perfect. For instance, it would match expressions like 23+48..6.1-64.5. Not likely to be a problem in these files, so I didn't tune it further.)

If the script doesn't find coordinates but does find something that looks like an address, it feeds the address into Google Maps and gets the resulting coordinates. That code looks like this:

from googlemaps import GoogleMaps

gmaps = GoogleMaps('YOUR GOOGLE MAPS API KEY HERE')
try:
    lat, lon = gmaps.address_to_latlng(addr)
except googlemaps.GoogleMapsError, e:
    print "Oh, no! Couldn't geocode", addr
    print e

Overall, a nice simple solution made possible with python-googlemaps. The full script is on github: waymaker.

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[ 11:24 Aug 20, 2013    More mapping | permalink to this entry | comments ]

Wed, 10 Jun 2009

Bing thinks we're WHERE?

Lots has been written about Bing, Microsoft's new search engine. It's better than Google, it's worse than Google, it'll never catch up to Google. Farhad Manjoo of Slate had perhaps the best reason to use Bing: "If you switch, Google's going to do some awesome things to try to win you back."

[Bing in Omniweb thinks we're in Portugal] But what I want to know about Bing is this: Why does it think we're in Portugal when Dave runs it under Omniweb on Mac?

In every other browser it gives the screen you've probably seen, with side menus (and a horizontal scrollbar if your window isn't wide enough, ugh) and some sort of pretty picture as a background. In Omniweb, you get a cleaner layout with no sidebars or horizontal scrollbars, a different pretty picture -- often prettier than the one you get on all the other browsers, though both images change daily -- and a set of togglebuttons that don't show up in any of the other browsers, letting you restrict results to only English or only results from Portugal.

Why does it think we're in Portugal when Dave uses Omniweb?

Equally puzzling, why do only people in Portugal have the option of restricting the results to English only?

Tags: , , ,
[ 09:37 Jun 10, 2009    More tech | permalink to this entry | comments ]

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