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import shapelib, dbflib, shptree |
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|
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# |
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# The the shapefile module |
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# |
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|
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def make_shapefile(filename): |
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obj = shapelib.SHPObject(shapelib.SHPT_POLYGON, 1, |
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[[(10, 10), (20, 10), (20, 20), (10, 10)]]) |
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print obj.extents() |
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print obj.vertices() |
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outfile = shapelib.create(filename, shapelib.SHPT_POLYGON) |
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outfile.write_object(-1, obj) |
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del outfile |
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|
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def read_shapefile(filename): |
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# open the shapefile |
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shp = shapelib.ShapeFile(filename) |
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|
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# the info method returns a tuple (num_shapes, type, min, max) where |
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# num_shapes is the number of shapes, type is the type code (one of |
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# the SHPT* constants defined in the shapelib module) and min and |
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# max are 4-element lists with the min. and max. values of the |
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# vertices. |
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print shp.info() |
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|
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# read_object reads a shape |
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obj = shp.read_object(0) |
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|
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# The vertices method returns the shape as a list of lists of tuples. |
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print obj.vertices()[0][:10] |
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|
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# The extents returns a tuple with two 4-element lists with the min. |
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# and max. values of the vertices. |
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print obj.extents() |
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|
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# The type attribute is the type code (one of the SHPT* constants |
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# defined in the shapelib module) |
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print obj.type |
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|
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# The id attribute is the shape id |
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print obj.id |
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|
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# the cobject method returns a PyCObject containing the shapelib |
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# SHPHandle. This is useful for passing shapefile objects to |
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# C-Python extensions. |
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print shp.cobject() |
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|
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# build a quad tree from the shapefile. The first argument must be |
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# the return value of the shape file object's cobject method (this |
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# is currently needed to access the shape file at the C-level). The |
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# second argument is the dimension and the third the maximum depth. |
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# 0 means to guess an appropriate depth |
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tree = shptree.SHPTree(shp.cobject(), 2, 0) |
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|
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# Retrieve the ids for a region. Here we just use the extents of the |
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# object previously read from the shapefile |
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minima, maxima = obj.extents() |
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print tree.find_shapes(minima[:2], maxima[:2]) |
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|
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|
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make_shapefile("testfile") |
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read_shapefile("testfile") |
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|
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# |
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# Test the DBF file module. |
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# |
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|
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def make_dbf(file): |
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# create a new dbf file and add three fields. |
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dbf = dbflib.create(file) |
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dbf.add_field("NAME", dbflib.FTString, 20, 0) |
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dbf.add_field("INT", dbflib.FTInteger, 10, 0) |
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dbf.add_field("FLOAT", dbflib.FTDouble, 10, 4) |
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|
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def add_dbf_records(file): |
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# add some records to file |
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dbf = dbflib.open(file, "r+b") |
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# Records can be added as a dictionary... |
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dbf.write_record(0, {'NAME': "Weatherwax", "INT":1, "FLOAT":3.1415926535}) |
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# ... or as a sequence |
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dbf.write_record(1, ("Ogg", 2, -1000.1234)) |
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|
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def list_dbf(file): |
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# print the contents of a dbf file to stdout |
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dbf = dbflib.DBFFile(file) |
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print "%d records, %d fields" % (dbf.record_count(), dbf.field_count()) |
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format = "" |
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for i in range(dbf.field_count()): |
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type, name, len, decc = dbf.field_info(i) |
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if type == 0: |
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format = format + " %%(%s)%ds" % (name, len) |
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elif type == 1: |
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format = format + " %%(%s)%dd" % (name, len) |
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elif type == 2: |
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format = format + " %%(%s)%dg" % (name, len) |
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print format |
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for i in range(dbf.record_count()): |
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print format % dbf.read_record(i) |
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|
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|
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make_dbf("testfile") |
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add_dbf_records("testfile") |
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list_dbf("testfile") |
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