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## Copyright (C) 2018-2020 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 {} {@var{out} =} gpxread (@var{fname})
## @deftypefnx {} {@var{out} =} gpxread (@var{fname}, @dots{})
## Read data from a gpx file.
##
## Input argument @var{fname} (a character string) can be a valid file
## name or a valid URL.
##
## If no other input arguments are given gpxread will read all data in
## @var{fname} into one output struct @var{out}. The data to be read can
## be selected and/or limited by specifying one or more of the following
## optional property/value pairs (all case-insensitive):
##
## @itemize
## @item "FeatureType'
## This option (a mere "f" suffices) can be one of:
## @table @asis
## @item
## "WayPoint or simply "w": Read waypoints.
## @end item
##
## @item
## "Track" or "t": read tracks.
## @end item
##
## @item
## "Route" or "t": read routes.
## @end item
##
## @item
## "Auto" or "a" (default value): read all data.
## @end item
## @end table
##
## Multiple FeatureType property/value pairs can be specified.
## @end item
##
## @item "Index"
## The ensuing Index value should be a numeric value, or numeric vector,
## of indices of the features to be read.
## @end item
## @end itemize
##
## Output argument @var{out} is a struct array with field names Name,
## Lat, Lon, Ele, Time, and -in case of routes- Names. "Name" refers
## to the name of the waypoints, tracks or routes that have been read.
## "Lat", "Lon" and "Ele" refer to the latitude, longitude and elevation
## of the various features, in case of tracks field "Time" refers to
## the time of the trackpoint. In case of tracks and routes these are
## vectors, each element corresponding to one track point. For each
## individual track multiple track segments are separated by NaNs. For
## routes the field "Names" contains a cell array holding the names of
## the individual route points.
##
## Examples:
##
## @example
## A = gpxread ("trip2.gpx", "feature", "track", "index", 2);
## (which returns data from the second track in file "trip1.gpx")
## @end example
##
## @example
## B = gpxread ("trip2.gpx", "f", "t", "f", "r");
## (which returns track and route data from file "trip2.gpx")
## @end example
##
## @end deftypefn
## Author: Philip Nienhuis <prnienhuis@users.sf.net>
## Created: 2017-02-05
function [outp] = gpxread (fname, varargin)
## Input validation
if (nargin < 1)
print_usage ();
elseif (! ischar (fname))
error ("gpread: file name expected for arg 1\n");
elseif (! isempty (cell2mat (cell2mat ...
(regexp (fname, '(ftp://|http://|file://)', "tokens")))))
url = true;
else
[pth, fnm, ext] = fileparts (fname);
if (isempty (ext))
fname = [fname ".gpx"];
endif
url = false;
endif
if (nargin < 2)
gtr = grt = gpt = 1;
else
gtr = grt = gpt = 0;
endif
if (mod (nargin, 2) != 1)
error ("gpxread: insufficient nr. of input arguments\n");
endif
idx = [];
for ii=1:2:numel (varargin)
if (ischar (varargin{ii}) && numel (varargin{ii}) > 0)
switch lower (varargin{ii})(1)
case "f"
switch lower (varargin{ii+1})(1)
case "t"
gtr = 1;
case "r"
grt = 1;
case "w"
gpt = 1;
case "a"
gtr = grt = gpt = 1;
otherwise
error ("gpxread: unknown FeatureType '%s'", varargin{ii+1});
endswitch
case "i"
idx = varargin{ii+1};
if (! isnumeric (idx))
error ("gpxread: numeric value or vector expected for arg.# %d\n", ii+1);
else
idx = uint32 (idx);
endif
otherwise
warning ("gpxread: unknown option '%s' - ignored\n", varargin{ii});
endswitch
else
error ("gpxread: wrong argument type for arg. %d - 'FeatureType' or \
'Index' expected", ii+1);
endif
endfor
if (url)
## Untested
xml = urlread (fname);
else
fid = fopen (fname, "r");
if (fid < 0)
error ("gpxread: couldn't open file %s\n", fname);
endif
xml = fread (fid, Inf, "char=>char")';
fclose (fid);
endif
outp = repmat (struct ("Type", "-", ...
"Lat", [], ...
"Lon", [], ...
"Ele", [], ...
"Time", [], ...
"Name", "-"), 0, 1);
if (gpt)
## (Try to) Read waypoints
ptrnp = 'wpt lat="(.*?)" lon="(.*?)">.*?ele>(.*?)</ele.*?name>(.*?)</name';
wpts = reshape (cell2mat ( regexp (xml, ptrnp, "tokens")'), [], 4);
if (! isempty (wpts))
wpts(:, 1:3) = num2cell (str2double (wpts(:, 1:3)));
if (isempty (idx))
idx = [1:size(wpts, 1)]';
else
idx(idx < 1) = [];
idx(idx > size (wpts, 1)) = [];
endif
[outp(1:numel (idx)).Name] = deal (wpts(idx, 4){:});
[outp(1:numel (idx)).Type] = deal ("WayPoint");
[outp(1:numel (idx)).Lat] = deal (wpts(idx, 1){:});
[outp(1:numel (idx)).Lon] = deal (wpts(idx, 2){:});
[outp(1:numel (idx)).Ele] = deal (wpts(idx, 3){:});
endif
endif
if (gtr)
## Read tracks
ptrnt1A = '<trkpt lat="(.*?)" lon="(.*?)".*?ele>(.*?)</ele>.*?<time>(.*?)</time';
ptrnt1B = '<trkpt lat="(.*?)" lon="(.*?)".*?time>(.*?)</time.*?ele>(.*?)</ele>';
ptrnt2 = '<trkpt lat="(.*?)" lon="(.*?)".*?ele>(.*?)</ele';
[trk, ~, is] = getxmlnode (xml, "trk", 1, 1);
itr = 0;
if (is != 0)
do
if (isempty (idx) || ismember (++itr, idx))
[trkseg, ~, ist] = getxmlnode (trk, "trkseg", 1, 1);
if (ist != 0)
outp(end+1).Type = "Track";
outp(end).Name = getxmlnode (trk, "name", 1, 1);
## Check if tracks have time node
it = index (trkseg, "</time>", "first");
## Check ele/time node order
if (it)
if (index (trkseg, "</ele>", "first") < it)
ptrnt = ptrnt1A;
dcol = 4;
else
ptrnt = ptrnt1B;
dcol = 3;
endif
ncols = 4;
else
ptrnt = ptrnt2;
ncols = 3;
endif
out = NaN (0, ncols);
do
arr = reshape (cell2mat (regexp (trkseg, ptrnt, "tokens")), ncols, [])';
if (ncols == 4)
arr = [ (str2double (arr(:, [1:2 7-dcol]))) (datenum (arr(:, dcol), "yyyy-mm-ddTHH:MM:SSZ")) ];
else
arr = str2double (arr);
endif
out = [out; arr; NaN(1, ncols)];
[trkseg, ~, ist] = getxmlnode (trk, "trkseg", ist, 1);
until (ist == 0);
out(end, :) = [];
outp(end).Lat = out(:, 1);
outp(end).Lon = out(:, 2);
outp(end).Ele = out(:, 3);
if (ncols == 4)
outp(end).Time = out(:, 4);
endif
endif
endif
[trk, ~, is] = getxmlnode (xml, "trk", is, 1);
until (is == 0);
endif
endif
if (grt)
## Read routes
ptrnr = 'rtept lat="(.*?)" lon="(.*?)".*?ele>(.*?)</ele.*?name>(.*?)</name';
[rte, ~, is] = getxmlnode (xml, "rte", 1, 1);
irt = 0;
if (is != 0)
do
if (isempty (idx) || ismember (++irt, idx))
outp(end+1).Type = "Route";
outp(end).Name = getxmlnode (rte, "name", 1, 1);
[rteseg, ~, isr] = getxmlnode (rte, "rtept", 1, 1);
rtp = reshape (cell2mat ( regexp (rte, ptrnr, "tokens")'), [], 4);
[outp(end).Lat] = str2double (rtp(:, 1));
[outp(end).Lon] = str2double (rtp(:, 2));
[outp(end).Ele] = str2double (rtp(:, 3));
[outp(end).Names] = rtp(:, 4);
endif
[rte, ~, is] = getxmlnode (xml, "rte", is, 1);
until (is == 0);
endif
endif
endfunction
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