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Re: Zip codes and Electoral districts

Posted by Tracey P. Lauriault-2 on Feb 09, 2007; 3:39am
URL: http://civicaccess.416.s1.nabble.com/Zip-codes-and-Electoral-districts-tp865p875.html

the lat long you get is a point, while the 6 digit postal code is a
polygon!  So for the data to be useful you also need the coordinates of
intersecting lines.


Frank Warmerdam wrote:

> Stéphane Zagar wrote:
>  
>> Hey
>>
>> In fact, technically it's not complicated to get a zip code mapping with
>> latitude and longitude :
>>
>> H3T1A1;45.5113;-73.6162
>>    
> ...
>  
>> H3T1Z1;45.4977;-73.6257
>>
>> And I think it's not that much complicated to do the same reverse
>> engineering for electoral district.
>>
>> The problem is that mathematically, there are about 17 millions of valid
>> combination of zip code. It take about 1 sec for my script to retrieve
>> the zipcode/lat-long so if we do a basic computation it gives us
>> about... 100 days to retrieve everything (and probably a lot of
>> bandwidth). Even if we set the last number to 1 (what I did in my
>> previous test), it's still about 2 millions valid values. And I'm not
>> sure if the website I use to retrieve this will allow this (with 1
>> request/sec, I can't imagine they won't see that something is happening).
>>    
>
> Stéphane,
>
> I'm afraid I haven't been following this thread very closely despite the
> fact that it is close to my heart.  But I'd assume the terms of use for
> the site do not allow you to extract their full database this way and
> redistribute it.  Is that not the case?
>
>  
>> By the way, I have a question for geostuff people (Tracey ?) : On the
>> geogratis website, there are some files concerning the electoral
>> districts (
>> http://geogratis.cgdi.gc.ca/geogratis/en/option/select.do?id=1169), but
>> I don't know anything concerning the format (Arc Export or shape file).
>> Is there a way to do something with that ? For example do a process
>> what-ever to find out in which electoral district is a point (long-lat) ?
>>    
>
> I can definitely help with this sort of thing if you want to do it.
> Geo-data-wrangling is my thing.
>
> Best regards,
>