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## Copyright (C) 2014,2015 Philip Nienhuis
##
## This program is free software; you can redistribute it and/or modify it
## under the terms of the GNU General Public License as published by
## the Free Software Foundation; either version 3 of the License, or
## (at your option) any later version.
##
## This program is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
## GNU General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with this program. If not, see <http://www.gnu.org/licenses/>.
## -*- texinfo -*-
## @deftypefn {Function File} {@var{status} =} shapewrite (@var{shpstr}, @var{fname})
## Write contents of map- or geostruct to a GIS shape file.
##
## @var{shpstr} must be a valid mapstruct or geostruct, a struct array with an
## entry for each shape feature, with fields Geometry, BoundingBox, and X and Y
## (mapstruct) or Lat and Lon (geostruct). For geostructs, Lat and Lon field
## data will be written as X and Y data. Field Geometry can have data values
## of "Point", "MultiPoint", "Line", or "Polygon", all case-insensitive. For
## each shape feature, field BoundingBox should contain the minimum and maximum
## (X,Y) coordinates in a 2x2 array [minX, minY; maxX, maxY]. The X and Y
## fields should contain X (or Latitude) and Y (or Longitude) coordinates for
## each point or vertex as row vectors; for polylines and polygons vertices of
## each subfeature (if present) should be separated by NaN entries.
##
## @var{fname} should be a valid shape file name, optionally with a '.shp'
## suffix.
##
## shapewrite produces 2 or 3 files, i.e. a .shp file (the actual shape file),
## a .shx file (index file), and if @var{shpstr} contained additional fields,
## a .dbf file (dBase type 3) with the contents of those additional fields.
##
## @var{status} is 1 if the shape file set was written successfully, 0
## otherwise.
##
## @seealso{shapedraw, shapeinfo, shaperead}
## @end deftypefn
## Author: Philip Nienhuis <prnienhuis@users.sf.net>
## Created: 2014-12-30
## 2015-06-26 Three fixes by Jan Heckman
function [status] = shapewrite (shp, fname, atts=[])
status = 0;
## Input validation
if (nargin < 1)
print_usage;
endif
## Assess shape variable type (oct or ml/geo ml/map)
if (! isstruct (shp))
error ("shapewrite: [map-, geo-] struct expected for argument #2");
else
## Yep. Find out what type
fldn = fieldnames (shp);
if (ismember ("vals", fldn) && ismember ("shpbox", fldn))
## Assume it is an Octave-style struct read by shaperead
otype = 0;
warning ("shapewrite: only Matlab-type map/geostructs can be written\n");
return;
elseif (ismember ("Geometry", fldn) && all (ismember ({"X", "Y"}, fldn)))
## Assume it is a Matlab-style mapstruct
otype = 1;
elseif (ismember ("Geometry", fldn) && all (ismember ({"Lat", "Lon"}, fldn)))
## Assume it is a Matlab-style geostruct
otype = 2;
else
## Not a supported struct type
error ("shapewrite: unsupported struct type.\n")
endif
if (any (ismember ({"M", "Z"}, fldn)))
otype = -otype;
endif
endif
## Check file name
[pth, fnm, ext] = fileparts (fname);
if (isempty (ext))
bname = fname;
fname = [fname ".shp"];
else
## Later on bname.shx and bname.dbf will be read
bname = [pth fnm];
endif
## Prepare a few things
numfeat = numel (shp);
if (abs (otype) >= 1)
stype = find (strcmpi (shp(1).Geometry, ...
{"Point", "MultiPoint", "Line", "Polygon"}));
stype = [1, 8, 3, 5](stype);
if (abs (otype) == 2)
## Change Lat/Lon fields into X/Y
[shp.X] = deal (shp.Lon);
[shp.Y] = deal (shp.Lat);
%% shp = rmfield (shp, {"Lat", "Lon"});
endif
## "Point" need not have a BoundingBox field => add a dummy if not found
if (stype == 1 && ! ismember ("BoundingBox", fldn))
[shp.BoundingBox] = deal (repmat (zeros (0, 0), numel (shp)));
endif
endif
## Only now (after input checks) open .shp and .shx files & rewind just to be sure
fids = fopen (fname, "w");
if (fids < 0)
error ("shapewrite: shapefile %s can't be opened for writing\n", fname);
endif
fseek (fids, 0, "bof");
fidx = fopen ([ bname ".shx" ], "w");
if (fidx < 0)
error ("shapewrite: indexfile %s can't be opened for writing\n", fname);
endif
fseek (fidx, 0, "bof");
## Write headers in .shp & .shx (identical). First magic number 9994 + 5 zeros
fwrite (fids, [9994 0 0 0 0 0 0], "int32", 0, "ieee-be");
fwrite (fidx, [9994 0 0 0 0 0], "int32", 0, "ieee-be");
## In between here = filelength in 16-bit words (single). For .shx it's known
fwrite (fidx, ((numfeat * 4) + 50), "int32", 0, "ieee-be");
## Next, shp file version
fwrite (fids, 1000, "int32");
fwrite (fidx, 1000, "int32");
## Shape feature type
fwrite (fids, stype, "int32");
fwrite (fidx, stype, "int32");
## Bounding box. Can be run later for ML type shape structs. Fill with zeros
fwrite (fids, [0 0 0 0 0 0 0 0], "double");
fwrite (fidx, [0 0 0 0 0 0 0 0], "double");
## Prepare BoundingBox limits
xMin = yMin = Inf;
xMax = yMax = -Inf;
## Skip to start of first record position
% fseek (fids, 100, "bof");
% fseek (fidx, 100, "bof");
## Write shape features one by one
if (abs (otype) >= 1)
for ishp=1:numfeat
## Write record start pos to .shx file
fwrite (fidx, ftell (fids) / 2, "int32", 0, "ieee-be");
## Write record contents
switch (stype)
case 1 ## Point
## Record index number
fwrite (fids, ishp, "int32", 0, "ieee-be");
## Record length (fixed)
reclen = 20;
fwrite (fids, reclen, "int32", 0, "ieee-be");
fwrite (fidx, reclen, "int32", 0, "ieee-be");
## Shape type
fwrite (fids, stype, "int32");
## Simply write XY cordinates
fwrite (fids, [shp(ishp).X shp(ishp).Y], "double");
## Update overall BoundingBox
xMin = min (xMin, shp(ishp).BoundingBox(1, 1));
xMax = max (xMax, shp(ishp).BoundingBox(1, 2));
yMin = min (yMin, shp(ishp).BoundingBox(2, 1));
yMax = max (yMax, shp(ishp).BoundingBox(2, 2));
case 8 ## MultiPoint
## Record index number
fwrite (fids, ishp, "int32", 0, "ieee-be");
## Record length
reclen = (48 + 16 * numel (shp(ishp).X)) / 2;
fwrite (fids, reclen, "int32", 0, "ieee-be");
fwrite (fidx, reclen, "int32", 0, "ieee-be");
## Shape type
fwrite (fids, stype, "int32");
## Bounding box
fwrite (fids, [shp(ishp).BoundingBox'(:)]', "double");
xMin = min (xMin, shp(ishp).BoundingBox(1, 1));
xMax = max (xMax, shp(ishp).BoundingBox(1, 2));
yMin = min (yMin, shp(ishp).BoundingBox(2, 1));
yMax = max (yMax, shp(ishp).BoundingBox(2, 2));
## Nr of points
fwrite (fids, numel (shp(ishp).X), "int32");
fwrite (fids, [shp(ishp).X shp(ishp).Y]', "double");
reclen = (44 + 16 * numel (shp(ishp).X)) / 2;
case {3, 5} ## Polyline/-gon
## Record index number
fwrite (fids, ishp, "int32", 0, "ieee-be");
## Prepare multipart polygons
idx = [ 0 find(isnan (shp(ishp).X)) ];
npt = numel (shp(ishp).X) - numel (idx) + 1;
## Augment idx for later on, & this trick eliminates trailing NaN rows
idx = unique ([ idx npt ]);
## Record length
reclen = (44 + (numel(idx)-1)*4 + 2*8*npt) / 2;
fwrite (fids, reclen, "int32", 0, "ieee-be");
fwrite (fidx, reclen, "int32", 0, "ieee-be");
## Shape type
fwrite (fids, stype, "int32");
## Bounding box
fwrite (fids, [shp(ishp).BoundingBox'(:)]', "double");
xMin = min (xMin, shp(ishp).BoundingBox(1, 1));
xMax = max (xMax, shp(ishp).BoundingBox(1, 2));
yMin = min (yMin, shp(ishp).BoundingBox(2, 1));
yMax = max (yMax, shp(ishp).BoundingBox(2, 2));
## Number of parts, number of points, part pointers
fwrite (fids, [(numel(idx)-1) npt idx(1:end-1) ], "int32");
for ii=1:numel(idx)-1
fwrite (fids, [shp(ishp).X(idx(ii)+1:idx(ii+1)) ...
shp(ishp).Y(idx(ii)+1:idx(ii+1))](:)', "double");
endfor
otherwise
## Future shape types or types unsupported yet (M, Z, MultiPatch)
endswitch
endfor
endif
## Write file length and overall BoundingBox into .shp header
flen = ftell (fids);
fseek (fids, 24, "bof");
fwrite (fids, flen/2, "int32", 0, "ieee-be");
fseek (fids, 36, "bof");
fwrite (fids, [xMin yMin xMax yMax], "double");
fseek (fidx, 36, "bof");
fwrite (fidx, [xMin yMin xMax yMax], "double");
## Close files
fclose (fids);
fclose (fidx);
## Check for dbfwrite function
if (isempty (which ("dbfwrite")))
printf ("shaperead.m: dbfwrite function not found. No attributes written.\n");
printf (" (io package 2.2.6+ installed and loaded?)\n");
return;
endif
## Write rest of attributes
if (nargin == 3)
shp = atts;
else
if (otype == 1)
## Attributes + shp data in mapstruct
shp = rmfield (shp, {"Geometry", "BoundingBox", "X", "Y"});
elseif (otype == 2)
## Attributes + shp data in geostruct
shp = rmfield (shp, {"Geometry", "BoundingBox", "Lat", "Lon", "X", "Y"});
endif
endif
attribs = cell (numfeat + 1, numel (fieldnames (shp)));
attribs(1, :) = fieldnames (shp);
attribs(2:end, :) = (squeeze (struct2cell (shp)))';
if (! isempty (attribs))
try
status = dbfwrite ([ bname ".dbf"], attribs);
catch
warning ("shapewrite: writing attributes to file %s failed\n", [bname ".dbf"]);
end_try_catch
else
status = 1;
endif
endfunction
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