/[thuban]/branches/WIP-pyshapelib-bramz/Thuban/Model/data.py

Diff of /branches/WIP-pyshapelib-bramz/Thuban/Model/data.py

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-revision 1515 by bh,
Tue Jul 29 14:59:11 2003 UTC
+revision 1972 by bh,
Mon Nov 24 19:23:08 2003 UTC
 Line 7
  """Data source abstractions"""
+ from __future__ import generators
  __version__ = "$Revision$"
  # $Source$
  # $Id$
  import os
  import weakref
+ from math import ceil, log
  import shapelib
+ import shptree
  import table
  import transientdb
  from Thuban import _
+ # Shape type constants
+ SHAPETYPE_POLYGON = "polygon"
+ SHAPETYPE_ARC = "arc"
+ SHAPETYPE_POINT = "point"
+ # mapping from shapelib shapetype constants to our constants
+ shapelib_shapetypes = {shapelib.SHPT_POLYGON: SHAPETYPE_POLYGON,
+                        shapelib.SHPT_ARC: SHAPETYPE_ARC,
+                        shapelib.SHPT_POINT: SHAPETYPE_POINT}
+ #
+ # Raw shape data formats
+ #
+ # Raw data is the same as that returned by the points method.
+ RAW_PYTHON = "RAW_PYTHON"
+ # Raw data is a shapefile. The Shape object will use the shapeid as the
+ # raw data.
+ RAW_SHAPEFILE = "RAW_SHAPEFILE"
+ # Raw data in well-known text format
+ RAW_WKT = "RAW_WKT"
+ class ShapefileShape:
+     """Represent one shape of a shapefile"""
+     def __init__(self, shapefile, shapeid):
+         self.shapefile = shapefile
+         self.shapeid = shapeid
+     def compute_bbox(self):
+         """
+         Return the bounding box of the shape as a tuple (minx,miny,maxx,maxy)
+         """
+         xs = []
+         ys = []
+         for part in self.Points():
+             for x, y in part:
+                 xs.append(x)
+                 ys.append(y)
+         return (min(xs), min(ys), max(xs), max(ys))
+     def ShapeID(self):
+         return self.shapeid
+     def Points(self):
+         """Return the coordinates of the shape as a list of lists of pairs"""
+         shape = self.shapefile.read_object(self.shapeid)
+         points = shape.vertices()
+         if self.shapefile.info()[1] == shapelib.SHPT_POINT:
+             points = [points]
+         return points
+     def RawData(self):
+         """Return the shape id to use with the shapefile"""
+         return self.shapeid
+     def Shapefile(self):
+         """Return the shapefile object"""
+         return self.shapefile
  class ShapeTable(transientdb.AutoTransientTable):
-Line 56 
 class ShapefileStore:
+Line 124 
 class ShapefileStore:
          # safer to always work with absolute paths.
          self.filename = os.path.abspath(filename)
-         self.shapefile = shapelib.ShapeFile(self.filename)
          self.dbftable = table.DBFTable(filename)
          self.table = ShapeTable(self, session.TransientDB(), self.dbftable)
+         self._open_shapefile()
+     def _open_shapefile(self):
+         self.shapefile = shapelib.ShapeFile(self.filename)
+         self.numshapes, shapetype, mins, maxs = self.shapefile.info()
+         if self.numshapes:
+             self.bbox = mins[:2] + maxs[:2]
+         else:
+             self.bbox = None
+         self.shapetype = shapelib_shapetypes[shapetype]
+         # estimate a good depth for the quad tree. Each depth multiplies
+         # the number of nodes by four, therefore we basically take the
+         # base 4 logarithm of the number of shapes.
+         if self.numshapes < 4:
+             maxdepth = 1
+         else:
+             maxdepth = int(ceil(log(self.numshapes / 4.0) / log(4)))
+         self.shapetree = shptree.SHPTree(self.shapefile.cobject(), 2,
+                                          maxdepth)
      def Table(self):
          """Return the table containing the attribute data"""
-Line 76 
 class ShapefileStore:
+Line 164 
 class ShapefileStore:
          """Return the filetype. This is always the string 'shapefile'"""
          return "shapefile"
+     def ShapeType(self):
+         """Return the type of the shapes in the shapestore.
+         This is either SHAPETYPE_POINT, SHAPETYPE_ARC or SHAPETYPE_POLYGON.
+         """
+         return self.shapetype
+     def RawShapeFormat(self):
+         """Return the raw data format of the shape data, i.e. RAW_SHAPEFILE"""
+         return RAW_SHAPEFILE
+     def NumShapes(self):
+         """Return the number of shapes in the shape store"""
+         return self.numshapes
      def Dependencies(self):
          """Return the empty tuple.
-Line 90 
 class ShapefileStore:
+Line 193 
 class ShapefileStore:
          """
          return None
+     def BoundingBox(self):
+         """Return the bounding box of the shapes in the shapestore.
+         The coordinate system used is whatever was used in the shapefile.
+         If the shapefile is empty, return None.
+         """
+         return self.bbox
+     def ShapesInRegion(self, bbox):
+         """Return an iterable over the shapes that overlap the bounding box.
+         The bbox parameter should be the bounding box as a tuple in the
+         form (minx, miny, maxx, maxy) in the coordinate system of the
+         shape store.
+         """
+         # Bind a few globals to locals to make it a bit faster
+         cls = ShapefileShape
+         shapefile = self.shapefile
+         left, bottom, right, top = bbox
+         for i in self.shapetree.find_shapes((left, bottom), (right, top)):
+             yield cls(shapefile, i)
+     def AllShapes(self):
+         """Return an iterable over the shapes in the shape store."""
+         for i in xrange(self.NumShapes()):
+             yield ShapefileShape(self.shapefile, i)
+     def Shape(self, index):
+         """Return the shape with index index"""
+         return ShapefileShape(self.shapefile, index)
  class DerivedShapeStore:
-Line 129 
 class DerivedShapeStore:
+Line 265 
 class DerivedShapeStore:
          Return the original shapestore the derived store was instantiated with
          """
          return self.shapestore
+     def Shape(self, index):
+         """Return the shape with index index"""
+         return self.shapestore.Shape(index)
+     def ShapesInRegion(self, bbox):
+         """Return the ids of the shapes that overlap the box.
+         This method is simply delegated to the shapestore the
+         DerivedShapeStore was instantiated with.
+         """
+         return self.shapestore.ShapesInRegion(bbox)
+     def AllShapes(self):
+         """Return an iterable over the shapes in the shape store.
+         This method is simply delegated to the shapestore the
+         DerivedShapeStore was instantiated with.
+         """
+         return self.shapestore.AllShapes()
+     def ShapeType(self):
+         """Return the type of the shapes in the layer.
+         This method is simply delegated to the shapestore the
+         DerivedShapeStore was instantiated with.
+         """
+         return self.shapestore.ShapeType()
+     def RawShapeFormat(self):
+         """Return the raw data format of the shapes.
+         This method is simply delegated to the shapestore the
+         DerivedShapeStore was instantiated with.
+         """
+         return self.shapestore.RawShapeFormat()
+     def NumShapes(self):
+         """Return the number of shapes in the shapestore."""
+         return self.shapestore.NumShapes()
+     def BoundingBox(self):
+         """Return the bounding box of the shapes in the shapestore.
+         This method is simply delegated to the shapestore the
+         DerivedShapeStore was instantiated with.
+         """
+         return self.shapestore.BoundingBox()

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 Legend:



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changed lines


 
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-Removed from v.1515
+Added in v.1972

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