[postgis-users] Finding/Categorizing Paths from A to B

[sub3]

>> So, I really want to find a way to look at the paths table and determine
>> that paths 1,2,3 I took 1st street. Path 4,5 I took 5th street. Path 6
>> started going on 1st street then switch over to 5 street.
>>
>> So if I looked at it graphically on a map, I could easily determine which
>> paths where which.
>
>Overlaying on a map should be easy: QGIS, etc.  Do you have a table of
>streets, if you need to see which street you went down (you need one)?

That is exactly what I want to do... but first I want to find a way to boil
down all trips to 12 or so distinct paths; without having to overlay every
trip.  But since I only have points, not streets; i have no way to say path
#1 is different from path #2.

So take the example path over a grid A->E by 1->5 where A1 is start, E5 is
the end.
I would have paths:
1 | Line(A1,B1,C1,D1,E1,E2,E3,E4,E5)
2 | Line(A1,A2,A3,A4,A5,B5,C5,D5,E5)
3 | Line(A1,A2,A3,B3,C3,D3,E3,E4,E5)
4 | Line(A1,B1,C1,D1,E1,E2,E3,E4,E5)
5 | Line(A1,B1,C1,D1,E1,E1,E1,E2,E3,E4,E5)

I would like to find out that 1 is the same path as 4 and 5, but I can't do
a direct 1==4. Since A1 is a
latitude/longitude from a GPS, it wouldn't be the exact A1 each time.  If I
traverse through A1, I might get lat/lon: 39.54/75.07 one day, while
39.53/75.08 the next day.  It would be the same road, just 200ft further
down it, based on when the gps record is taken.

After I find the distinct paths,I can easily find avg time/speed based on
rows 1,4,5; since they are really the same.

Thanks.






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