function [att_val, att_names] = attnc(file, var_name, att_name)%attnc returns selected attributes of the named netCDF file.%--------------------------------------------------------------------% DESCRIPTION:%%  [att_val, att_names] = attnc(file, var_name, att_name)%        INPUT%  file: the name of a netCDF file with or without the .cdf or .nc extent.%  var_name: a string containing the name of the variable whose%    attribute is required.  A global attribute may be specified by%    passing the string 'global'.%  att_name: a string containing the name of the attribute that is%    required.  If att_name is not specified then it is assumed that the%    user wants all of the attributes.%        OUTPUT%  att_val: If att_name is specified then its value is returned in att_val.%    If att_name is not specified then the values of all of the attributes%    are returned in the cell att_val.%%  att_names: If att_name is specified then the sane name is returned in%    att_names provided that the attribute is found (otherwise it is%    empty).  If att_name is not specified then the names of all of the%    attributes are returned in the cell att_names.%%  Note 1) If only 2 arguments are passed to attnc then all of the%    attributes and their names (for the specified variable) are returned.%  Note 2) If only 1 argument is passed to attnc then all of the global%    attributes and their names are returned.%  Note 3) If the file is in compressed form then the user will be%  given an option for automatic uncompression.%% CALLER:   general purpose% CALLEE:   check_nc.m, ncmex.mex, netcdf toolbox%% AUTHOR:   J. V. Mansbridge, CSIRO%---------------------------------------------------------------------%     Copyright (C), J.V. Mansbridge, %     Commonwealth Scientific and Industrial Research Organisation%     Revision $Revision: 1.4 $%     Author   $Author: man133 $%     Date     $Date: 2004/12/22 05:49:48 $%     RCSfile  $RCSfile: attnc.m,v $% @(#)attnc.m   1.5   92/05/26% % Note that the netcdf functions are accessed by reference to the mex% function ncmex.%--------------------------------------------------------------------% Check the number of arguments.if ( nargin < 1 | nargin > 3 )   help attnc   returnend% Do some initialisation.blank = abs(' ');if nargin == 1  var_name = 'global';end% Check that the file is accessible.  If it is then its full name will% be stored in the variable cdf.  The file may have the extent .cdf or% .nc and be in the current directory or the common data set (whose% path can be found by a call to pos_cds.m.  If a compressed form% of the file is in the current directory then the user is prompted to% uncompress it.  If, after all this, the netcdf file is not accessible% then the m file is exited with an error message.cdf_list = { '' '.nc' '.cdf'};ilim = length(cdf_list);for i = 1:ilim   cdf = [ file cdf_list{i} ];  err = check_nc(cdf);  if err == 0    break;  elseif err == 1    if i == ilim      error([ file ' could not be found' ])    end  elseif err == 2    path_name = pos_cds;    cdf = [ path_name cdf ];    break;  elseif err == 3    err1 = uncmp_nc(cdf);    if err1 == 0      break;    elseif err1 == 1      disp([ 'exiting because you chose not to uncompress ' cdf ])      return;    elseif err1 == 2      error([ 'exiting because ' cdf ' could not be uncompressed' ])    end  endend% Open the netcdf file.  [cdfid, rcode] = ncmex('ncopen', cdf, 'nowrite');% don't print out netcdf warning messagesncmex('setopts',0);if rcode == -1  error([ 'ncmex: ncopen: rcode = ' int2str(rcode) ])end%According to the value of nargin either find and store all of the%global attributes of the cdf file or only one specific value.att_val = [];att_names = [];if strcmp(var_name, 'global')  %Collect information about the cdf file.  [ndims, nvars, ngatts, recdim, rcode] =  ncmex('ncinquire', cdfid);  if rcode == -1    error([ 'ncmex: ncinquire: rcode = ' int2str(rcode) ])  end  if nargin < 3    if ngatts > 0      for i = 0:ngatts-1	[attnam, rcode] = ncmex('attname', cdfid, 'global', i);	[attype, attlen, rcode] = ncmex('ncattinq', cdfid, 'global', attnam);	[values, rcode] = ncmex('ncattget', cdfid, 'global', attnam);	att_val{i+1} = values;	att_names{i+1} = attnam;      end    else      disp('   ---  There are no Global attributes  ---')    end  else    if ngatts > 0      found_it = 0;      for i = 0:ngatts-1	[attnam, rcode] = ncmex('attname', cdfid, 'global', i);	if strcmp(attnam, att_name)	  found_it = 1;	  [attype, attlen, rcode] = ncmex('ncattinq', cdfid, 'global', attnam);	  [values, rcode] = ncmex('ncattget', cdfid, 'global', attnam);	  att_val = values;	  att_names = attnam;	  break	end      end      if found_it == 0	warning([ 'the attribute ' att_name ' was not found'])      end    else      warning([ 'the attribute ' att_name ' was not found'])    end  endelse  varid = ncmex('VARID', cdfid, var_name);  if varid == -1    error([ 'ncmex: varid: ' var_name ' is not a variable' ])  end  [varname, datatype, ndims, dim, natts, rcode] = ...      ncmex('VARINQ', cdfid, varid);  if nargin < 3    if natts > 0      for i = 0:natts-1	[attnam, rcode] = ncmex('attname', cdfid, varid, i);	[attype, attlen, rcode] = ncmex('ncattinq', cdfid, varid, attnam);	[values, rcode] = ncmex('ncattget', cdfid, varid, attnam);	att_val{i+1} = values;	att_names{i+1} = attnam;      end    else      disp(['   ---   ' varid ' has no attributes  ---'])    end  else    if natts > 0      found_it = 0;      for i = 0:natts-1	[attnam, rcode] = ncmex('attname', cdfid, varid, i);	if strcmp(attnam, att_name)	  found_it = 1;	  [attype, attlen, rcode] = ncmex('ncattinq', cdfid, varid, attnam);	  [values, rcode] = ncmex('ncattget', cdfid, varid, attnam);	  att_val = values;	  att_names = attnam;	  break	end      end      if found_it == 0	warning([ 'the attribute ' att_name ' was not found'])      end    else      warning([ 'the attribute ' att_name ' was not found'])    end  endend% Close the netcdf file.[rcode] = ncmex('ncclose', cdfid);if rcode == -1  error(['** ERROR ** ncclose: rcode = ' num2str(rcode)])end