3.5 KiB
{{{ #!python from ufpy.dataaccess import DataAccessLayer from shapely.geometry import Polygon,Point from datetime import datetime
#Initiate a new DataRequest #Get all of the states from the database print "Requesting all states from DAF" t1=datetime.utcnow() request = DataAccessLayer.newDataRequest() request.setDatatype("maps") request.addIdentifier("geomField","the_geom") request.addIdentifier("table","mapdata.states") request.setParameters("state","fips","name") states = DataAccessLayer.getGeometryData(request, None) t2=datetime.utcnow() tdelta = t2-t1 print 'DAF query to get all states took %i.%i seconds' %(tdelta.seconds,tdelta.microseconds)
#Create a polygon object...for example this is a polygon around Oklahoma City polygon = Polygon([(-97.82,35.63),(-97.21,35.63),(-97.21,35.15),(-97.82,35.15),(-97.82,35.63)]) #Now lets filter the states down to the one that contains the above polygon #We will use the python built in filter method to accomplish this #the expression below goes through each state object, gets it's geometry, and calls #it's contains method. It in essence creates a new list, state_contain_polygon, with #only the states where the contains method evaluates to true. t1=datetime.utcnow() state_contain_polygon = filter(lambda state: state.getGeometry().contains(polygon),states) t2= datetime.utcnow() tdelta = t2-t1 print '\nFilter state objects to one that contains polygon took %i.%i seconds' %(tdelta.seconds,tdelta.microseconds) print state_contain_polygon print "Polygon is in the state of",state_contain_polygon[0].getString('name')
#Lets also create a point object...this one is located in the state of Iowa point = Point(-93.62,41.60) #Now lets see what state our point is in t1=datetime.utcnow() state_contain_point = filter(lambda state: state.getGeometry().contains(point),states) t2= datetime.utcnow() tdelta = t2-t1 print '\nFilter state objects to one that contains point took %i.%i seconds ' %(tdelta.seconds,tdelta.microseconds) print state_contain_point print "Point is in the state of",state_contain_point[0].getString('name')
#One last example...this time for an intersection. Lets find all of the states this polygon intersects #This polygon is the same as above just extended it further south to 33.15 degrees polygon2 = Polygon([(-97.82,35.63),(-97.21,35.63),(-97.21,33.15),(-97.82,33.15),(-97.82,35.63)]) t1=datetime.utcnow() state_intersect_polygon = filter(lambda state: state.getGeometry().intersects(polygon2),states) t2= datetime.utcnow() tdelta = t2-t1 print '\nFilter state objects to the ones that intersect polygon took %i.%i seconds ' %(tdelta.seconds,tdelta.microseconds) print state_intersect_polygon for state in state_intersect_polygon: print "Polygon intersects the state of",state.getString('name') }}}
{{{ Requesting all states from DAF DAF query to get all states took 21.915029 seconds }}}
{{{ Filter state objects to one that contains polygon took 0.382097 seconds [<ufpy.dataaccess.PyGeometryData.PyGeometryData object at 0x2bebdd0>] Polygon is in the state of Oklahoma }}}
{{{ Filter state objects to one that contains point took 0.2028 seconds [<ufpy.dataaccess.PyGeometryData.PyGeometryData object at 0x2beb9d0>] Point is in the state of Iowa }}}
{{{ Filter state objects to the ones that intersect polygon took 0.4032 seconds [<ufpy.dataaccess.PyGeometryData.PyGeometryData object at 0x2beb610>, <ufpy.dataaccess.PyGeometryData.PyGeometryData object at 0x2bebdd0>] Polygon intersects the state of Texas Polygon intersects the state of Oklahoma }}}