-
Notifications
You must be signed in to change notification settings - Fork 2
/
shapefile.py
1192 lines (1120 loc) · 46.1 KB
/
shapefile.py
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
"""
shapefile.py
Provides read and write support for ESRI Shapefiles.
author: jlawhead<at>geospatialpython.com
date: 20140507
version: 1.2.1
Compatible with Python versions 2.4-3.x
version changelog: Fixed u() to just return the byte sequence on exception
"""
__version__ = "1.2.1"
from struct import pack, unpack, calcsize, error
import os
import sys
import time
import array
import tempfile
import itertools
#
# Constants for shape types
NULL = 0
POINT = 1
POLYLINE = 3
POLYGON = 5
MULTIPOINT = 8
POINTZ = 11
POLYLINEZ = 13
POLYGONZ = 15
MULTIPOINTZ = 18
POINTM = 21
POLYLINEM = 23
POLYGONM = 25
MULTIPOINTM = 28
MULTIPATCH = 31
PYTHON3 = sys.version_info[0] == 3
if PYTHON3:
xrange = range
def b(v):
if PYTHON3:
if isinstance(v, str):
# For python 3 encode str to bytes.
return v.encode('utf-8')
elif isinstance(v, bytes):
# Already bytes.
return v
else:
# Error.
raise Exception('Unknown input type')
else:
# For python 2 assume str passed in and return str.
return v
def u(v):
if PYTHON3:
# try/catch added 2014/05/07
# returned error on dbf of shapefile
# from www.naturalearthdata.com named
# "ne_110m_admin_0_countries".
# Just returning v as is seemed to fix
# the problem. This function could
# be condensed further.
try:
if isinstance(v, bytes):
# For python 3 decode bytes to str.
return v.decode('utf-8')
elif isinstance(v, str):
# Already str.
return v
else:
# Error.
raise Exception('Unknown input type')
except: return v
else:
# For python 2 assume str passed in and return str.
return v
def is_string(v):
if PYTHON3:
return isinstance(v, str)
else:
return isinstance(v, basestring)
class _Array(array.array):
"""Converts python tuples to lits of the appropritate type.
Used to unpack different shapefile header parts."""
def __repr__(self):
return str(self.tolist())
def signed_area(coords):
"""Return the signed area enclosed by a ring using the linear time
algorithm at http://www.cgafaq.info/wiki/Polygon_Area. A value >= 0
indicates a counter-clockwise oriented ring.
"""
xs, ys = map(list, zip(*coords))
xs.append(xs[1])
ys.append(ys[1])
return sum(xs[i]*(ys[i+1]-ys[i-1]) for i in range(1, len(coords)))/2.0
class _Shape:
def __init__(self, shapeType=None):
"""Stores the geometry of the different shape types
specified in the Shapefile spec. Shape types are
usually point, polyline, or polygons. Every shape type
except the "Null" type contains points at some level for
example verticies in a polygon. If a shape type has
multiple shapes containing points within a single
geometry record then those shapes are called parts. Parts
are designated by their starting index in geometry record's
list of shapes."""
self.shapeType = shapeType
self.points = []
@property
def __geo_interface__(self):
if self.shapeType in [POINT, POINTM, POINTZ]:
return {
'type': 'Point',
'coordinates': tuple(self.points[0])
}
elif self.shapeType in [MULTIPOINT, MULTIPOINTM, MULTIPOINTZ]:
return {
'type': 'MultiPoint',
'coordinates': tuple([tuple(p) for p in self.points])
}
elif self.shapeType in [POLYLINE, POLYLINEM, POLYLINEZ]:
if len(self.parts) == 1:
return {
'type': 'LineString',
'coordinates': tuple([tuple(p) for p in self.points])
}
else:
ps = None
coordinates = []
for part in self.parts:
if ps == None:
ps = part
continue
else:
coordinates.append(tuple([tuple(p) for p in self.points[ps:part]]))
ps = part
else:
coordinates.append(tuple([tuple(p) for p in self.points[part:]]))
return {
'type': 'MultiLineString',
'coordinates': tuple(coordinates)
}
elif self.shapeType in [POLYGON, POLYGONM, POLYGONZ]:
if len(self.parts) == 1:
return {
'type': 'Polygon',
'coordinates': (tuple([tuple(p) for p in self.points]),)
}
else:
ps = None
coordinates = []
for part in self.parts:
if ps == None:
ps = part
continue
else:
coordinates.append(tuple([tuple(p) for p in self.points[ps:part]]))
ps = part
else:
coordinates.append(tuple([tuple(p) for p in self.points[part:]]))
polys = []
poly = [coordinates[0]]
for coord in coordinates[1:]:
if signed_area(coord) < 0:
polys.append(poly)
poly = [coord]
else:
poly.append(coord)
polys.append(poly)
if len(polys) == 1:
return {
'type': 'Polygon',
'coordinates': tuple(polys[0])
}
elif len(polys) > 1:
return {
'type': 'MultiPolygon',
'coordinates': polys
}
class _ShapeRecord:
"""A shape object of any type."""
def __init__(self, shape=None, record=None):
self.shape = shape
self.record = record
class ShapefileException(Exception):
"""An exception to handle shapefile specific problems."""
pass
class Reader:
"""Reads the three files of a shapefile as a unit or
separately. If one of the three files (.shp, .shx,
.dbf) is missing no exception is thrown until you try
to call a method that depends on that particular file.
The .shx index file is used if available for efficiency
but is not required to read the geometry from the .shp
file. The "shapefile" argument in the constructor is the
name of the file you want to open.
You can instantiate a Reader without specifying a shapefile
and then specify one later with the load() method.
Only the shapefile headers are read upon loading. Content
within each file is only accessed when required and as
efficiently as possible. Shapefiles are usually not large
but they can be.
"""
def __init__(self, *args, **kwargs):
self.shp = None
self.shx = None
self.dbf = None
self.shapeName = "Not specified"
self._offsets = []
self.shpLength = None
self.numRecords = None
self.fields = []
self.__dbfHdrLength = 0
# See if a shapefile name was passed as an argument
if len(args) > 0:
if is_string(args[0]):
self.load(args[0])
return
if "shp" in kwargs.keys():
if hasattr(kwargs["shp"], "read"):
self.shp = kwargs["shp"]
if hasattr(self.shp, "seek"):
self.shp.seek(0)
if "shx" in kwargs.keys():
if hasattr(kwargs["shx"], "read"):
self.shx = kwargs["shx"]
if hasattr(self.shx, "seek"):
self.shx.seek(0)
if "dbf" in kwargs.keys():
if hasattr(kwargs["dbf"], "read"):
self.dbf = kwargs["dbf"]
if hasattr(self.dbf, "seek"):
self.dbf.seek(0)
if self.shp or self.dbf:
self.load()
else:
raise ShapefileException("Shapefile Reader requires a shapefile or file-like object.")
def load(self, shapefile=None):
"""Opens a shapefile from a filename or file-like
object. Normally this method would be called by the
constructor with the file object or file name as an
argument."""
if shapefile:
(shapeName, ext) = os.path.splitext(shapefile)
self.shapeName = shapeName
try:
self.shp = open("%s.shp" % shapeName, "rb")
except IOError:
raise ShapefileException("Unable to open %s.shp" % shapeName)
try:
self.shx = open("%s.shx" % shapeName, "rb")
except IOError:
raise ShapefileException("Unable to open %s.shx" % shapeName)
try:
self.dbf = open("%s.dbf" % shapeName, "rb")
except IOError:
raise ShapefileException("Unable to open %s.dbf" % shapeName)
if self.shp:
self.__shpHeader()
if self.dbf:
self.__dbfHeader()
def __getFileObj(self, f):
"""Checks to see if the requested shapefile file object is
available. If not a ShapefileException is raised."""
if not f:
raise ShapefileException("Shapefile Reader requires a shapefile or file-like object.")
if self.shp and self.shpLength is None:
self.load()
if self.dbf and len(self.fields) == 0:
self.load()
return f
def __restrictIndex(self, i):
"""Provides list-like handling of a record index with a clearer
error message if the index is out of bounds."""
if self.numRecords:
rmax = self.numRecords - 1
if abs(i) > rmax:
raise IndexError("Shape or Record index out of range.")
if i < 0: i = range(self.numRecords)[i]
return i
def __shpHeader(self):
"""Reads the header information from a .shp or .shx file."""
if not self.shp:
raise ShapefileException("Shapefile Reader requires a shapefile or file-like object. (no shp file found")
shp = self.shp
# File length (16-bit word * 2 = bytes)
shp.seek(24)
self.shpLength = unpack(">i", shp.read(4))[0] * 2
# Shape type
shp.seek(32)
self.shapeType= unpack("<i", shp.read(4))[0]
# The shapefile's bounding box (lower left, upper right)
self.bbox = _Array('d', unpack("<4d", shp.read(32)))
# Elevation
self.elevation = _Array('d', unpack("<2d", shp.read(16)))
# Measure
self.measure = _Array('d', unpack("<2d", shp.read(16)))
def __shape(self):
"""Returns the header info and geometry for a single shape."""
f = self.__getFileObj(self.shp)
record = _Shape()
nParts = nPoints = zmin = zmax = mmin = mmax = None
(recNum, recLength) = unpack(">2i", f.read(8))
# Determine the start of the next record
next = f.tell() + (2 * recLength)
shapeType = unpack("<i", f.read(4))[0]
record.shapeType = shapeType
# For Null shapes create an empty points list for consistency
if shapeType == 0:
record.points = []
# All shape types capable of having a bounding box
elif shapeType in (3,5,8,13,15,18,23,25,28,31):
record.bbox = _Array('d', unpack("<4d", f.read(32)))
# Shape types with parts
if shapeType in (3,5,13,15,23,25,31):
nParts = unpack("<i", f.read(4))[0]
# Shape types with points
if shapeType in (3,5,8,13,15,23,25,31):
nPoints = unpack("<i", f.read(4))[0]
# Read parts
if nParts:
record.parts = _Array('i', unpack("<%si" % nParts, f.read(nParts * 4)))
# Read part types for Multipatch - 31
if shapeType == 31:
record.partTypes = _Array('i', unpack("<%si" % nParts, f.read(nParts * 4)))
# Read points - produces a list of [x,y] values
if nPoints:
record.points = [_Array('d', unpack("<2d", f.read(16))) for p in range(nPoints)]
# Read z extremes and values
if shapeType in (13,15,18,31):
(zmin, zmax) = unpack("<2d", f.read(16))
record.z = _Array('d', unpack("<%sd" % nPoints, f.read(nPoints * 8)))
# Read m extremes and values if header m values do not equal 0.0
if shapeType in (13,15,18,23,25,28,31) and not 0.0 in self.measure:
(mmin, mmax) = unpack("<2d", f.read(16))
# Measure values less than -10e38 are nodata values according to the spec
record.m = []
for m in _Array('d', unpack("<%sd" % nPoints, f.read(nPoints * 8))):
if m > -10e38:
record.m.append(m)
else:
record.m.append(None)
# Read a single point
if shapeType in (1,11,21):
record.points = [_Array('d', unpack("<2d", f.read(16)))]
# Read a single Z value
if shapeType == 11:
record.z = unpack("<d", f.read(8))
# Read a single M value
if shapeType in (11,21):
record.m = unpack("<d", f.read(8))
# Seek to the end of this record as defined by the record header because
# the shapefile spec doesn't require the actual content to meet the header
# definition. Probably allowed for lazy feature deletion.
f.seek(next)
return record
def __shapeIndex(self, i=None):
"""Returns the offset in a .shp file for a shape based on information
in the .shx index file."""
shx = self.shx
if not shx:
return None
if not self._offsets:
# File length (16-bit word * 2 = bytes) - header length
shx.seek(24)
shxRecordLength = (unpack(">i", shx.read(4))[0] * 2) - 100
numRecords = shxRecordLength // 8
# Jump to the first record.
shx.seek(100)
for r in range(numRecords):
# Offsets are 16-bit words just like the file length
self._offsets.append(unpack(">i", shx.read(4))[0] * 2)
shx.seek(shx.tell() + 4)
if not i == None:
return self._offsets[i]
def shape(self, i=0):
"""Returns a shape object for a shape in the the geometry
record file."""
shp = self.__getFileObj(self.shp)
i = self.__restrictIndex(i)
offset = self.__shapeIndex(i)
if not offset:
# Shx index not available so iterate the full list.
for j,k in enumerate(self.iterShapes()):
if j == i:
return k
shp.seek(offset)
return self.__shape()
def shapes(self):
"""Returns all shapes in a shapefile."""
shp = self.__getFileObj(self.shp)
# Found shapefiles which report incorrect
# shp file length in the header. Can't trust
# that so we seek to the end of the file
# and figure it out.
shp.seek(0,2)
self.shpLength = shp.tell()
shp.seek(100)
shapes = []
while shp.tell() < self.shpLength:
shapes.append(self.__shape())
return shapes
def iterShapes(self):
"""Serves up shapes in a shapefile as an iterator. Useful
for handling large shapefiles."""
shp = self.__getFileObj(self.shp)
shp.seek(0,2)
self.shpLength = shp.tell()
shp.seek(100)
while shp.tell() < self.shpLength:
yield self.__shape()
def __dbfHeaderLength(self):
"""Retrieves the header length of a dbf file header."""
if not self.__dbfHdrLength:
if not self.dbf:
raise ShapefileException("Shapefile Reader requires a shapefile or file-like object. (no dbf file found)")
dbf = self.dbf
(self.numRecords, self.__dbfHdrLength) = \
unpack("<xxxxLH22x", dbf.read(32))
return self.__dbfHdrLength
def __dbfHeader(self):
"""Reads a dbf header. Xbase-related code borrows heavily from ActiveState Python Cookbook Recipe 362715 by Raymond Hettinger"""
if not self.dbf:
raise ShapefileException("Shapefile Reader requires a shapefile or file-like object. (no dbf file found)")
dbf = self.dbf
headerLength = self.__dbfHeaderLength()
numFields = (headerLength - 33) // 32
for field in range(numFields):
fieldDesc = list(unpack("<11sc4xBB14x", dbf.read(32)))
name = 0
idx = 0
if b("\x00") in fieldDesc[name]:
idx = fieldDesc[name].index(b("\x00"))
else:
idx = len(fieldDesc[name]) - 1
fieldDesc[name] = fieldDesc[name][:idx]
fieldDesc[name] = u(fieldDesc[name])
fieldDesc[name] = fieldDesc[name].lstrip()
fieldDesc[1] = u(fieldDesc[1])
self.fields.append(fieldDesc)
terminator = dbf.read(1)
if terminator != b("\r"):
raise ShapefileException("Shapefile dbf header lacks expected terminator. (likely corrupt?)")
self.fields.insert(0, ('DeletionFlag', 'C', 1, 0))
def __recordFmt(self):
"""Calculates the size of a .shp geometry record."""
if not self.numRecords:
self.__dbfHeader()
fmt = ''.join(['%ds' % fieldinfo[2] for fieldinfo in self.fields])
fmtSize = calcsize(fmt)
return (fmt, fmtSize)
def __record(self):
"""Reads and returns a dbf record row as a list of values."""
f = self.__getFileObj(self.dbf)
recFmt = self.__recordFmt()
recordContents = unpack(recFmt[0], f.read(recFmt[1]))
if recordContents[0] != b(' '):
# deleted record
return None
record = []
for (name, typ, size, deci), value in zip(self.fields,
recordContents):
if name == 'DeletionFlag':
continue
elif not value.strip():
record.append(value)
continue
elif typ == "N":
value = value.replace(b('\0'), b('')).strip()
value = value.replace(b('*'), b('')) # QGIS NULL is all '*' chars
if value == b(''):
value = None
elif deci:
value = float(value)
else:
value = int(value)
elif typ == b('D'):
if value.count(b('0')) == len(value): # QGIS NULL is all '0' chars
value = None
else:
try:
y, m, d = int(value[:4]), int(value[4:6]), int(value[6:8])
value = [y, m, d]
except:
value = value.strip()
elif typ == b('L'):
value = (value in b('YyTt') and b('T')) or \
(value in b('NnFf') and b('F')) or b('?')
else:
value = u(value)
value = value.strip()
record.append(value)
return record
def record(self, i=0):
"""Returns a specific dbf record based on the supplied index."""
f = self.__getFileObj(self.dbf)
if not self.numRecords:
self.__dbfHeader()
i = self.__restrictIndex(i)
recSize = self.__recordFmt()[1]
f.seek(0)
f.seek(self.__dbfHeaderLength() + (i * recSize))
return self.__record()
def records(self):
"""Returns all records in a dbf file."""
if not self.numRecords:
self.__dbfHeader()
records = []
f = self.__getFileObj(self.dbf)
f.seek(self.__dbfHeaderLength())
for i in range(self.numRecords):
r = self.__record()
if r:
records.append(r)
return records
def iterRecords(self):
"""Serves up records in a dbf file as an iterator.
Useful for large shapefiles or dbf files."""
if not self.numRecords:
self.__dbfHeader()
f = self.__getFileObj(self.dbf)
f.seek(self.__dbfHeaderLength())
for i in xrange(self.numRecords):
r = self.__record()
if r:
yield r
def shapeRecord(self, i=0):
"""Returns a combination geometry and attribute record for the
supplied record index."""
i = self.__restrictIndex(i)
return _ShapeRecord(shape=self.shape(i), record=self.record(i))
def shapeRecords(self):
"""Returns a list of combination geometry/attribute records for
all records in a shapefile."""
shapeRecords = []
return [_ShapeRecord(shape=rec[0], record=rec[1]) \
for rec in zip(self.shapes(), self.records())]
def iterShapeRecords(self):
"""Returns a generator of combination geometry/attribute records for
all records in a shapefile."""
for shape, record in itertools.izip(self.iterShapes(), self.iterRecords()):
yield _ShapeRecord(shape=shape, record=record)
class Writer:
"""Provides write support for ESRI Shapefiles."""
def __init__(self, shapeType=None):
self._shapes = []
self.fields = []
self.records = []
self.shapeType = shapeType
self.shp = None
self.shx = None
self.dbf = None
# Geometry record offsets and lengths for writing shx file.
self._offsets = []
self._lengths = []
# Use deletion flags in dbf? Default is false (0).
self.deletionFlag = 0
def __getFileObj(self, f):
"""Safety handler to verify file-like objects"""
if not f:
raise ShapefileException("No file-like object available.")
elif hasattr(f, "write"):
return f
else:
pth = os.path.split(f)[0]
if pth and not os.path.exists(pth):
os.makedirs(pth)
return open(f, "wb")
def __shpFileLength(self):
"""Calculates the file length of the shp file."""
# Start with header length
size = 100
# Calculate size of all shapes
for s in self._shapes:
# Add in record header and shape type fields
size += 12
# nParts and nPoints do not apply to all shapes
#if self.shapeType not in (0,1):
# nParts = len(s.parts)
# nPoints = len(s.points)
if hasattr(s,'parts'):
nParts = len(s.parts)
if hasattr(s,'points'):
nPoints = len(s.points)
# All shape types capable of having a bounding box
if self.shapeType in (3,5,8,13,15,18,23,25,28,31):
size += 32
# Shape types with parts
if self.shapeType in (3,5,13,15,23,25,31):
# Parts count
size += 4
# Parts index array
size += nParts * 4
# Shape types with points
if self.shapeType in (3,5,8,13,15,23,25,31):
# Points count
size += 4
# Points array
size += 16 * nPoints
# Calc size of part types for Multipatch (31)
if self.shapeType == 31:
size += nParts * 4
# Calc z extremes and values
if self.shapeType in (13,15,18,31):
# z extremes
size += 16
# z array
size += 8 * nPoints
# Calc m extremes and values
if self.shapeType in (23,25,31):
# m extremes
size += 16
# m array
size += 8 * nPoints
# Calc a single point
if self.shapeType in (1,11,21):
size += 16
# Calc a single Z value
if self.shapeType == 11:
size += 8
# Calc a single M value
if self.shapeType in (11,21):
size += 8
# Calculate size as 16-bit words
size //= 2
return size
def __bbox(self, shapes, shapeTypes=[]):
x = []
y = []
for s in shapes:
shapeType = self.shapeType
if shapeTypes:
shapeType = shapeTypes[shapes.index(s)]
px, py = list(zip(*s.points))[:2]
x.extend(px)
y.extend(py)
return [min(x), min(y), max(x), max(y)]
def __zbox(self, shapes, shapeTypes=[]):
z = []
for s in shapes:
try:
for p in s.points:
z.append(p[2])
except IndexError:
pass
if not z: z.append(0)
return [min(z), max(z)]
def __mbox(self, shapes, shapeTypes=[]):
m = [0]
for s in shapes:
try:
for p in s.points:
m.append(p[3])
except IndexError:
pass
return [min(m), max(m)]
def bbox(self):
"""Returns the current bounding box for the shapefile which is
the lower-left and upper-right corners. It does not contain the
elevation or measure extremes."""
return self.__bbox(self._shapes)
def zbox(self):
"""Returns the current z extremes for the shapefile."""
return self.__zbox(self._shapes)
def mbox(self):
"""Returns the current m extremes for the shapefile."""
return self.__mbox(self._shapes)
def __shapefileHeader(self, fileObj, headerType='shp'):
"""Writes the specified header type to the specified file-like object.
Several of the shapefile formats are so similar that a single generic
method to read or write them is warranted."""
f = self.__getFileObj(fileObj)
f.seek(0)
# File code, Unused bytes
f.write(pack(">6i", 9994,0,0,0,0,0))
# File length (Bytes / 2 = 16-bit words)
if headerType == 'shp':
f.write(pack(">i", self.__shpFileLength()))
elif headerType == 'shx':
f.write(pack('>i', ((100 + (len(self._shapes) * 8)) // 2)))
# Version, Shape type
f.write(pack("<2i", 1000, self.shapeType))
# The shapefile's bounding box (lower left, upper right)
if self.shapeType != 0:
try:
f.write(pack("<4d", *self.bbox()))
except error:
raise ShapefileException("Failed to write shapefile bounding box. Floats required.")
else:
f.write(pack("<4d", 0,0,0,0))
# Elevation
z = self.zbox()
# Measure
m = self.mbox()
try:
f.write(pack("<4d", z[0], z[1], m[0], m[1]))
except error:
raise ShapefileException("Failed to write shapefile elevation and measure values. Floats required.")
def __dbfHeader(self):
"""Writes the dbf header and field descriptors."""
f = self.__getFileObj(self.dbf)
f.seek(0)
version = 3
year, month, day = time.localtime()[:3]
year -= 1900
# Remove deletion flag placeholder from fields
for field in self.fields:
if field[0].startswith("Deletion"):
self.fields.remove(field)
numRecs = len(self.records)
numFields = len(self.fields)
headerLength = numFields * 32 + 33
recordLength = sum([int(field[2]) for field in self.fields]) + 1
header = pack('<BBBBLHH20x', version, year, month, day, numRecs,
headerLength, recordLength)
f.write(header)
# Field descriptors
for field in self.fields:
name, fieldType, size, decimal = field
name = b(name)
name = name.replace(b(' '), b('_'))
name = name.ljust(11).replace(b(' '), b('\x00'))
fieldType = b(fieldType)
size = int(size)
fld = pack('<11sc4xBB14x', name, fieldType, size, decimal)
f.write(fld)
# Terminator
f.write(b('\r'))
def __shpRecords(self):
"""Write the shp records"""
f = self.__getFileObj(self.shp)
f.seek(100)
recNum = 1
for s in self._shapes:
self._offsets.append(f.tell())
# Record number, Content length place holder
f.write(pack(">2i", recNum, 0))
recNum += 1
start = f.tell()
# Shape Type
if self.shapeType != 31:
s.shapeType = self.shapeType
f.write(pack("<i", s.shapeType))
# All shape types capable of having a bounding box
if s.shapeType in (3,5,8,13,15,18,23,25,28,31):
try:
f.write(pack("<4d", *self.__bbox([s])))
except error:
raise ShapefileException("Falied to write bounding box for record %s. Expected floats." % recNum)
# Shape types with parts
if s.shapeType in (3,5,13,15,23,25,31):
# Number of parts
f.write(pack("<i", len(s.parts)))
# Shape types with multiple points per record
if s.shapeType in (3,5,8,13,15,23,25,31):
# Number of points
f.write(pack("<i", len(s.points)))
# Write part indexes
if s.shapeType in (3,5,13,15,23,25,31):
for p in s.parts:
f.write(pack("<i", p))
# Part types for Multipatch (31)
if s.shapeType == 31:
for pt in s.partTypes:
f.write(pack("<i", pt))
# Write points for multiple-point records
if s.shapeType in (3,5,8,13,15,23,25,31):
try:
[f.write(pack("<2d", *p[:2])) for p in s.points]
except error:
raise ShapefileException("Failed to write points for record %s. Expected floats." % recNum)
# Write z extremes and values
if s.shapeType in (13,15,18,31):
try:
f.write(pack("<2d", *self.__zbox([s])))
except error:
raise ShapefileException("Failed to write elevation extremes for record %s. Expected floats." % recNum)
try:
if hasattr(s,"z"):
f.write(pack("<%sd" % len(s.z), *s.z))
else:
[f.write(pack("<d", p[2])) for p in s.points]
except error:
raise ShapefileException("Failed to write elevation values for record %s. Expected floats." % recNum)
# Write m extremes and values
if s.shapeType in (13,15,18,23,25,28,31):
try:
if hasattr(s,"m"):
f.write(pack("<%sd" % len(s.m), *s.m))
else:
f.write(pack("<2d", *self.__mbox([s])))
except error:
raise ShapefileException("Failed to write measure extremes for record %s. Expected floats" % recNum)
try:
[f.write(pack("<d", p[3])) for p in s.points]
except error:
raise ShapefileException("Failed to write measure values for record %s. Expected floats" % recNum)
# Write a single point
if s.shapeType in (1,11,21):
try:
f.write(pack("<2d", s.points[0][0], s.points[0][1]))
except error:
raise ShapefileException("Failed to write point for record %s. Expected floats." % recNum)
# Write a single Z value
if s.shapeType == 11:
if hasattr(s, "z"):
try:
if not s.z:
s.z = (0,)
f.write(pack("<d", s.z[0]))
except error:
raise ShapefileException("Failed to write elevation value for record %s. Expected floats." % recNum)
else:
try:
if len(s.points[0])<3:
s.points[0].append(0)
f.write(pack("<d", s.points[0][2]))
except error:
raise ShapefileException("Failed to write elevation value for record %s. Expected floats." % recNum)
# Write a single M value
if s.shapeType in (11,21):
if hasattr(s, "m"):
try:
if not s.m:
s.m = (0,)
f.write(pack("<1d", s.m[0]))
except error:
raise ShapefileException("Failed to write measure value for record %s. Expected floats." % recNum)
else:
try:
if len(s.points[0])<4:
s.points[0].append(0)
f.write(pack("<1d", s.points[0][3]))
except error:
raise ShapefileException("Failed to write measure value for record %s. Expected floats." % recNum)
# Finalize record length as 16-bit words
finish = f.tell()
length = (finish - start) // 2
self._lengths.append(length)
# start - 4 bytes is the content length field
f.seek(start-4)
f.write(pack(">i", length))
f.seek(finish)
def __shxRecords(self):
"""Writes the shx records."""
f = self.__getFileObj(self.shx)
f.seek(100)
for i in range(len(self._shapes)):
f.write(pack(">i", self._offsets[i] // 2))
f.write(pack(">i", self._lengths[i]))
def __dbfRecords(self):
"""Writes the dbf records."""
f = self.__getFileObj(self.dbf)
for record in self.records:
if not self.fields[0][0].startswith("Deletion"):
f.write(b(' ')) # deletion flag
for (fieldName, fieldType, size, dec), value in zip(self.fields, record):
fieldType = fieldType.upper()
size = int(size)
if fieldType.upper() == "N":
value = str(value).rjust(size)
elif fieldType == 'L':
value = str(value)[0].upper()
else:
value = str(value)[:size].ljust(size)
if len(value) != size:
raise ShapefileException(
"Shapefile Writer unable to pack incorrect sized value"
" (size %d) into field '%s' (size %d)." % (len(value), fieldName, size))
value = b(value)
f.write(value)
def null(self):
"""Creates a null shape."""
self._shapes.append(_Shape(NULL))
def point(self, x, y, z=0, m=0):
"""Creates a point shape."""
pointShape = _Shape(self.shapeType)
pointShape.points.append([x, y, z, m])
self._shapes.append(pointShape)
def line(self, parts=[], shapeType=POLYLINE):
"""Creates a line shape. This method is just a convienience method
which wraps 'poly()'.
"""
self.poly(parts, shapeType, [])
def poly(self, parts=[], shapeType=POLYGON, partTypes=[]):
"""Creates a shape that has multiple collections of points (parts)
including lines, polygons, and even multipoint shapes. If no shape type
is specified it defaults to 'polygon'. If no part types are specified
(which they normally won't be) then all parts default to the shape type.
"""
polyShape = _Shape(shapeType)
polyShape.parts = []
polyShape.points = []
# Make sure polygons are closed
if shapeType in (5,15,25,31):
for part in parts:
if part[0] != part[-1]:
part.append(part[0])
for part in parts:
polyShape.parts.append(len(polyShape.points))
for point in part:
# Ensure point is list
if not isinstance(point, list):
point = list(point)
# Make sure point has z and m values
while len(point) < 4:
point.append(0)
polyShape.points.append(point)
if polyShape.shapeType == 31:
if not partTypes:
for part in parts:
partTypes.append(polyShape.shapeType)
polyShape.partTypes = partTypes
self._shapes.append(polyShape)
def field(self, name, fieldType="C", size="50", decimal=0):
"""Adds a dbf field descriptor to the shapefile."""
self.fields.append((name, fieldType, size, decimal))
def record(self, *recordList, **recordDict):
"""Creates a dbf attribute record. You can submit either a sequence of
field values or keyword arguments of field names and values. Before
adding records you must add fields for the record values using the
fields() method. If the record values exceed the number of fields the
extra ones won't be added. In the case of using keyword arguments to specify
field/value pairs only fields matching the already registered fields
will be added."""
record = []
fieldCount = len(self.fields)
# Compensate for deletion flag
if self.fields[0][0].startswith("Deletion"): fieldCount -= 1
if recordList:
[record.append(recordList[i]) for i in range(fieldCount)]
elif recordDict:
for field in self.fields:
if field[0] in recordDict:
val = recordDict[field[0]]
if val is None:
record.append("")
else:
record.append(val)
if record:
self.records.append(record)
def shape(self, i):
return self._shapes[i]
def shapes(self):