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## Copyright (C) 2012, 2013, 2015 Alexander Barth <barth.alexander@gmail.com>
##
## 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/>.
## Author: Alexander Barth (barth.alexander@gmail.com)
## -*- texinfo -*-
## @deftypefn {} {[@var{dims}, @var{coord}] =} nccoord(@var{filename}, @var{varname})
## Get coordinates of the variable varname in the
## netcdf file called filename. The netcdf is assumed to
## follow the CF convention.
##
## @subsubheading Inputs
## @var{filename} - netcdf filename
##
## @var{varname} - variable name
##
## @subsubheading Outputs
## @var{dims} - a cell-array of the dimensions of varname
##
## @var{coord} - an array of structures with the field 'name'
## for the variable name, 'dims' with a cell-array of the
## netcdf dimensions, the units and NetCDF-CF standard name.
##
## coord is an empty structure if no coordinate information have been
## found.
## @end deftypefn
## TODO: use a predictable order for coord:
## lon, lat, depth, time, ensemble,...
function [dims,coord] = nccoord(filename,varname)
if ischar(filename)
finfo = ncinfo(filename);
else
finfo = filename;
endif
% get variable info
index = find(strcmp({finfo.Variables(:).Name},varname));
vinfo = finfo.Variables(index);
% determine coordinates
% using CF convention
dims = {vinfo.Dimensions(:).Name};
% create empty coord array with the fields name and dims
coord = struct('name',{},'dims',{},'standard_name',{},...
'units',{},'positive',{});
% check the coordinate attribute
if ~isempty(vinfo.Attributes)
index = find(strcmp('coordinates',{vinfo.Attributes(:).Name}));
if ~isempty(index)
tmp = strsplit(vinfo.Attributes(index).Value,' ');
% order should not be siginficant
for i=length(tmp):-1:1
coord = addcoord(coord,tmp{i},finfo);
endfor
endif
endif
% check for coordinate dimensions
for i=1:length(dims)
% check if variable with the same name than the dimension exist
index = find(strcmp(dims{i},{finfo.Variables(:).Name}),1);
if ~isempty(index)
coord = addcoord(coord,dims{i},finfo);
endif
endfor
endfunction
function coord = addcoord(coord,name,finfo)
% check if coordinate is aleady in the list
if isempty(find(strcmp(name,{coord(:).name}),1))
% check if name is variable
index = find(strcmp(name,{finfo.Variables(:).Name}));
if ~isempty(index)
vinfo = finfo.Variables(index);
c.name = name;
d = vinfo.Dimensions;
c.dims = {d(:).Name};
c.standard_name = [];
c.units = [];
c.positive = [];
% get standard_name attribute if present
i = find(strcmp('standard_name',{vinfo.Attributes(:).Name}));
if ~isempty(i)
c.standard_name = vinfo.Attributes(i).Value;
endif
% get units attribute if present
i = find(strcmp('units',{vinfo.Attributes(:).Name}));
if ~isempty(i)
c.units = vinfo.Attributes(i).Value;
endif
% get positive attribute if present
i = find(strcmp('positive',{vinfo.Attributes(:).Name}));
if ~isempty(i)
c.positive = vinfo.Attributes(i).Value;
endif
coord(end+1) = c;
endif
endif
endfunction
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