spatial_reference

Sometimes I need to search an EPSG from spatialreferece.org.

execfile("spatial_reference.py")
print SpatialReference.epsg_search("Florida West")
[('26759', 'NAD27 / Florida West'), ('26959', 'NAD83 / Florida West')]

Also, sometimes I want to guess the projection of a set of points which I do not have any clue about it:

execfile("spatial_reference.py")
points = [(7647409.02929, 686790.02595000004), (7647471.0159499999, 688344.44999999995),  (7645653.23905, 684826.79570999998), (7645656.2857100004, 684567.37809999997)]
epsgs = SpatialReference.guess_the_projection(points, state="Oregon")
for epsg, hits in epsgs[:5]:
    print "[EPSG:%d] %.0f%% hit" % (epsg, float(hits)/len(points)*100.0)

which returns:

[EPSG:2269] 100% hit
[EPSG:2913] 100% hit
[EPSG:3646] 100% hit
[EPSG:2270] 0% hit
[EPSG:2838] 0% hit
[EPSG:2839] 0% hit

This function tries to figure out the projection of these points by trying all the projections with "Oregon" in their description in spatialreferece.org then checks if the transformed points fall within the bounding box of Oregon with a known projection.

Other examples:

# some points in Dallas
points = [(2514332.03903053, 7018364.6881987797), (2503623.9508441598, 6974201.6616298398), (2499328.3021238302, 6939465.4717225898), (2499328.3021238302, 6939465.4717225898), (2499328.3021238302, 6939465.4717225898)]
epsgs = SpatialReference.guess_the_projection(points, state="Texas")
for epsg, hits in epsgs[:5]:
    print "[EPSG:%d] %.0f%% hit" % (epsg, float(hits)/len(points)*100.0)

[EPSG:2276] 100% hit
[EPSG:2917] 100% hit
[EPSG:3670] 100% hit
[EPSG:2275] 0% hit
[EPSG:2277] 0% hit

The points could be in feet, so we can do:

# some points in St. Louis :
points = [(894672.5, 995003.69999999995), (900456.30000000005, 1017035.0), (900456.30000000005, 1017035.0), (882164.59999999998, 999102.19999999995), (891889.30000000005, 1034635.0), (898334.0, 1022420.0), (894343.0, 1005425.0), (893510.30000000005, 1033772.0), (883747.80000000005, 1004093.0), (877404.59999999998, 1027557.0)]
epsgs = SpatialReference.guess_the_projection(points, state="Missouri", city="St. Louis", conversion=SpatialReference.meter_to_feet)
for epsg, hits in epsgs[:5]:
    print "[EPSG:%d] %.0f%% hit" % (epsg, float(hits)/len(points)*100.0)

[EPSG:2815] 100% hit
[EPSG:3602] 100% hit
[EPSG:26996] 100% hit
[EPSG:2816] 0% hit
[EPSG:2817] 0% hit