CODEWITHSUNDEEP
pythongdalwkt
Theo F
Theo F

Reputation: 1365

Extract XY extent from WKT string

Using python, how can I extract the XY extent of a WKT polygon? I need it in gdal compatible format like: minx miny maxx maxy

So for example below, I'd need to convert wkt to be wkt_extent:

wkt = "Polygon ((366247 156971, 366247 174054, 383331 174054, 383331 156971, 366247 156971))"
# need xy bounding box coordinates of wkt, as shown below
wkt_extent = "366247 156971 383331 174054"

Please keep in mind that the wkt is not always a rectangle/square and is not always 'drawn' in a clockwise direction like the example wkt shown here.

SRID here is 27700 and units are in meters.

Upvotes: 1

Views: 1849

Answers (2)

bm13563
bm13563

Reputation: 698

Assuming your WKT is passed as a string:

def parse_geometry(geometry):
    regex = r'[0-9-\.]+'
    parsed_geom = re.findall(regex, geometry)
    parsed_geom = [float(i) for i in parsed_geom]
    return max(parsed_geom[::2]), min(parsed_geom[::2]), max(parsed_geom[1::2]), min(parsed_geom[1::2])

Upvotes: 1

Rutger Kassies
Rutger Kassies

Reputation: 64443

If you don't mind a dependency on GDAL/OGR, you can use this:

geom = ogr.CreateGeometryFromWkt(wkt)
extent = geom.GetEnvelope()

The extent will be a tuple: (366247.0, 383331.0, 156971.0, 174054.0)

Having the extra dependency is of course a downside, but OGR does handle the parsing/validation for you.

Upvotes: 1

Related Questions