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gistfile1.py
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"""
Parses and converts the Flickr Shapefiles Public Dataset, Version 1.0
http://code.flickr.com/blog/2009/05/21/flickr-shapefiles-public-dataset-10/
"""
 
import sys
from datetime import date
import osgeo.ogr, osgeo.osr
from osgeo import ogr, osr
import xml.sax
from xml.sax import SAXException
from xml.sax.handler import ContentHandler
 
class FlickrShapeParser(ContentHandler):
def getLayer(self, name):
return self.layer
 
layer = self.shp.GetLayerByName(name)
 
if layer == None:
layer = self.shp.CreateLayer(name, geom_type=ogr.wkbPolygon, srs=self.srs)
layer.CreateField(ogr.FieldDefn("woe_id", ogr.OFTInteger))
layer.CreateField(ogr.FieldDefn("place_id", ogr.OFTString))
layer.CreateField(ogr.FieldDefn("place_type", ogr.OFTString))
layer.CreateField(ogr.FieldDefn("label", ogr.OFTString))
layer.CreateField(ogr.FieldDefn("alpha", ogr.OFTReal))
layer.CreateField(ogr.FieldDefn("donuthole", ogr.OFTInteger))
layer.CreateField(ogr.FieldDefn("points", ogr.OFTInteger))
layer.CreateField(ogr.FieldDefn("edges", ogr.OFTInteger))
layer.CreateField(ogr.FieldDefn("created", ogr.OFTDate))
 
return layer
 
def startDocument(self):
self.stack = []
 
self.srs = osr.SpatialReference()
self.srs.ImportFromProj4('+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs')
 
driver = ogr.GetDriverByName('ESRI Shapefile')
self.shp = driver.CreateDataSource('flickr.shp')
# create a dummy layer in the base shapefile to keep it empty
self.layer = self.shp.CreateLayer('Flickr Alpha Shapes', geom_type=ogr.wkbPolygon, srs=self.srs)
self.layer.CreateField(ogr.FieldDefn("woe_id", ogr.OFTInteger))
self.layer.CreateField(ogr.FieldDefn("place_id", ogr.OFTString))
self.layer.CreateField(ogr.FieldDefn("place_type", ogr.OFTString))
self.layer.CreateField(ogr.FieldDefn("label", ogr.OFTString))
self.layer.CreateField(ogr.FieldDefn("alpha", ogr.OFTReal))
self.layer.CreateField(ogr.FieldDefn("donuthole", ogr.OFTInteger))
self.layer.CreateField(ogr.FieldDefn("points", ogr.OFTInteger))
self.layer.CreateField(ogr.FieldDefn("edges", ogr.OFTInteger))
self.layer.CreateField(ogr.FieldDefn("created", ogr.OFTDate))
 
def endDocument(self):
self.shp.Destroy()
 
def startElement(self, name, attrs):
self.stack.append((name, attrs.copy()))
 
if name == "places":
pass
elif name == "place":
self.place_type_id = int(attrs.getValue("place_type_id"))
self.woe_id = int(attrs.getValue("woe_id"))
self.place_id = attrs.getValue("place_id")
self.place_type = attrs.getValue("place_type")
self.label = attrs.getValue("label")
 
print "%s (%s)" % (self.label.encode('utf-8'), self.woe_id)
elif name == "shape":
self.alpha = float(attrs.getValue("alpha"))
self.is_donuthole = int(attrs.getValue("is_donuthole"))
self.points = int(attrs.getValue("points"))
self.edges = int(attrs.getValue("edges"))
self.created = date.fromtimestamp(float(attrs.getValue("created")))
elif name == "shapefile":
self.url = attrs.getValue("url")
elif name == "polylines":
self.bbox = attrs.getValue("bbox")
self.rings = []
elif name == "polyline":
self.current_ring = ""
 
def endElement(self, name):
(_, attrs) = self.stack.pop()
 
if name == "places":
pass
if name == "place":
self.place_type_id = None
self.woe_id = None
self.place_id = None
self.place_type = None
self.label = None
elif name == "shape":
self.alpha = None
self.is_donuthole = None
self.points = None
self.edges = None
self.created = None
elif name == "shapefile":
self.url = None
elif name == "polylines":
self.bbox = None
wkt = "POLYGON ("
for ring in self.rings:
wkt += "(" + ring + ")"
 
wkt += ")"
 
poly = ogr.CreateGeometryFromWkt(wkt)
 
layer = self.getLayer(self.created.strftime("%B %Y"))
 
feature = ogr.Feature(feature_def=layer.GetLayerDefn())
feature.SetGeometryDirectly(poly)
feature.SetField(feature.GetFieldIndex("woe_id"), self.woe_id)
feature.SetField(feature.GetFieldIndex("place_id"), self.place_id)
feature.SetField(feature.GetFieldIndex("place_type"), self.place_type)
feature.SetField(feature.GetFieldIndex("label"), self.label.encode('utf-8'))
feature.SetField(feature.GetFieldIndex("alpha"), self.alpha)
feature.SetField(feature.GetFieldIndex("donuthole"), self.is_donuthole)
feature.SetField(feature.GetFieldIndex("points"), self.points)
feature.SetField(feature.GetFieldIndex("edges"), self.edges)
feature.SetField(feature.GetFieldIndex("created"), self.created)
 
layer.CreateFeature(feature)
 
feature.Destroy()
 
self.rings = None
elif name == "polyline":
# transform coordinates
r = []
for coords in self.current_ring.split(" "):
(y, x) = coords.split(",")
r.append(x + " " + y)
 
self.rings.append(",".join(r))
self.current_ring = ""
def characters(self, content):
(name, attrs) = self.stack[-1]
if name == "polyline":
self.current_ring += content
 
parser = FlickrShapeParser()
xml.sax.parse(sys.stdin, parser)

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