115 lines
3.7 KiB
Python
Executable file
115 lines
3.7 KiB
Python
Executable file
#!/usr/bin/env python
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# Utility to interrogate ESRI shape files
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import os
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import sys
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import struct
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ShapeType = { 0 : "NullShape",
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1 : "Point",
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3 : "PolyLine",
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5 : "Polygon",
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8 : "MultiPoint",
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11: "PointZ",
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13: "PolyLineZ",
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15: "PolygonZ",
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18: "MultiPointZ",
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21: "PointM",
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23: "PolyLineM",
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25: "PolygonM",
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28: "MultiPointM",
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31: "MultiPatch"}
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def test_record(_type, record) :
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if _type == 0:
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print("NULL shape")
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elif _type == 11: #PointZ
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test_pointz(record)
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elif _type == 5:
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test_polygon(record)
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def test_pointz(record):
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_type, = struct.unpack("<i", record[0:4])
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if _type == 0:
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print("NULL shape")
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return
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if len(record) != 36 :
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print("BAD SHAPE FILE: expected 36 bytes got", len(record), file=sys.stderr)
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sys.exit(1)
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x,y,z,m = struct.unpack("<dddd",record[4:36])
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if _type != 11:
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print("BAD SHAPE FILE: expected PointZ or NullShape got", _type, file=sys.stderr)
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sys.exit(1)
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def test_polygon(record):
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_type, = struct.unpack("<i", record[0:4])
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if _type == 0:
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print("NULL shape")
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return
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x0, y0, x1, y0, num_parts, num_points = struct.unpack("<ddddii", record[4:44])
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if _type != 5:
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print("BAD SHAPE FILE: expected Polygon or NullShape got", _type, file=sys.stderr)
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sys.exit(1)
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length = len(record)
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rec_length = 44 + num_parts * 4 + num_points * 16
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if rec_length != length:
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print("BAD SHAPE FILE: expected", rec_length, "got", length, file=sys.stderr)
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sys.exit(1)
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if __name__ == "__main__" :
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if len(sys.argv) !=2:
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print("Usage:",sys.argv[0],"<shapefile>", file=sys.stderr)
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sys.exit(1)
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shx_filename = sys.argv[1][:-3]+"shx"
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shp_filename = sys.argv[1][:-3]+"shp"
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shx = open(shx_filename)
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shp = open(shp_filename)
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header = (struct.Struct(">IIIIIII"),struct.Struct("<IIdddddddd"))
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# SHX header
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_,_,_,_,_,_,shx_file_length = header[0].unpack_from(shx.read(28))
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_,_,lox,loy,hix,hiy,_,_,_,_ = header[1].unpack_from(shx.read(72))
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shx_bbox = [lox,loy,hix,hiy]
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# SHP header
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_,_,_,_,_,_,shp_file_length = header[0].unpack_from(shp.read(28))
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version,_type,lox,loy,hix,hiy,_,_,_,_ = header[1].unpack_from(shp.read(72))
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shp_bbox = [lox,loy,hix,hiy]
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if shx_bbox != shp_bbox :
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print("BAD SHAPE FILE: bounding box mismatch in *.shp and *.shx", shp_bbox, shx_bbox)
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sys.exit(1)
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print("SHX FILE_LENGTH=",shx_file_length,"bytes")
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print("SHP FILE_LENGTH=",shp_file_length,"bytes")
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print("TYPE", ShapeType[_type])
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print("BBOX(",lox,loy,hix,hiy,")")
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record_header = struct.Struct(">II")
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record = struct.Struct(">II")
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calc_total_size = 50
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count = 0
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while shx.tell() <= shx_file_length * 2 - 4 * 2 :
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offset,shx_content_length = record.unpack_from(shx.read(8))
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shp.seek(offset*2, os.SEEK_SET)
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record_number,content_length = record_header.unpack_from(shp.read(8))
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if shx_content_length != content_length:
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print("BAD SHAPE FILE: content_lenght mismatch in SHP and SHX",shx_content_length,content_length)
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sys.exit(1)
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##
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test_record(_type, shp.read(2*content_length))
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calc_total_size +=(4 + content_length)
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count+=1
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print("SHAPES COUNT=",count)
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delta = shp_file_length-calc_total_size
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if delta > 0 :
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print("BAD SHAPE FILE: extra ", 2*delta,"bytes")
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elif delta < 0:
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print("BAD SHAPE FILE: missing ", 2*delta,"bytes")
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else:
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print("SHAPE FILE LOOKS GOOD!")
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