bin/path2pop

   1 #!/usr/bin/env python
   2
   3 """
   4 We take a Well-Known Text string and one or more KML files as
   5 parameters. We convert the WKT string to a polygon, and drag that
   6 polygon along the paths defined within the KML files. For each path,
   7 the result is another (longer) polygon, whose contained population is
   8 output.
   9 """
  10
  11 import os
  12 import site
  13 import sys
  14
  15
  16 # Basically, add '../src' to our path.
  17 # Needed for the imports that follow.
  18 site.addsitedir(os.path.dirname(os.path.abspath(sys.argv[0])) + '/../src')
  19
  20 import Census
  21 import CLI
  22 import Configuration.Defaults
  23 import ExitCodes
  24 import Geometry
  25 import KML
  26
  27 usage = '%prog [options] <well-known text> <kml file #1>, [kml file #2,...]'
  28
  29 # -h (help) Conflicts with -h HOSTNAME
  30 parser = CLI.default_option_parser(usage)
  31
  32 # Use this module's docstring as the description.
  33 parser.description = __doc__.strip()
  34
  35 parser.add_option('-s',
  36                   '--srid',
  37                   type="int",
  38                   help="SRID of the input geometry. Defaults to %s." % Configuration.Defaults.SRID,
  39                   default=Configuration.Defaults.SRID)
  40
  41 (options, args) = parser.parse_args()
  42
  43 if len(args) < 2:
  44     print """
  45 ERROR: You must supply both a Well-Known Text string, and a KML file
  46        containing a linestring.
  47 """
  48     parser.print_help()
  49     print '' # Print a newline
  50     raise SystemExit(ExitCodes.NOT_ENOUGH_ARGS)
  51
  52
  53 wkt_string = args[0]
  54 paths = args[1:]
  55
  56 for path in paths:
  57     f = open(path, 'r')
  58     kml = f.read()
  59     f.close()
  60
  61     coords = KML.LineString.tuples_from_kml(kml)
  62     p = Geometry.Polygon.from_wkt(wkt_string)
  63
  64     death_tube = None
  65
  66     for i in range(len(coords) - 1):
  67         # For each coordinate (except the last), we want to:
  68         # a) Translate our polygon to the coordinate.
  69         # b) Drag the polygon to the next coordinate.
  70         this_coord = Geometry.TwoVector(coords[i][0], coords[i][1])
  71         next_coord = Geometry.TwoVector(coords[i+1][0], coords[i+1][1])
  72         drag_vector = (next_coord - this_coord)
  73         tp = p.translate(this_coord)
  74
  75         if (death_tube == None):
  76             death_tube = tp.drag(drag_vector)
  77         else:
  78             death_tube = death_tube.union(tp.drag(drag_vector))
  79
  80     cdb = Census.Database(options.host,
  81                           options.database,
  82                           options.username,
  83                           options.srid)
  84
  85     pop = cdb.find_contained_population(death_tube.wkt())
  86
  87     print "Path: %s; Population: %d" % (path, pop)