script demo: native function

UPDATED VERSION: Here

function ncvardata=GetNcVarMatlab(ncfile,ncvar,RangeStr)
% to read data from the netcdf file using native matlab netcdf-functions
% Usage: vardata=GetNcVarMatlab(nc-filename,nc-varname,Dimension-Range)
% e.g.,
% mydata=GetNcVarMatlab('mask.nc','tmask','1:1,1:46,1:400,1:568');
% RangeStr here is similar to the output of ncdump
% copyright by http://scriptdemo.blogspot.com

IsDebug=0;
if ~exist(ncfile,'file')
   error([ncfile,' can not been found']);
   return
end

ncfid=netcdf.open(ncfile,'NC_NOWRITE');
% get dimension length
[numdims, numvars, numglobalatts, unlimdimID] = netcdf.inq(ncfid);
for NDim=1:numdims
      [dimname{NDim}, dimlen(NDim)] = netcdf.inqDim(ncfid,NDim-1);
end

%var infor
varid=netcdf.inqVarID(ncfid,ncvar);
[varname,varxtype,vardimids,varnumatts]=netcdf.inqVar(ncfid,varid);
numdims=length(vardimids); % some variables may have less dimensions

if ~exist('RangeStr','var')
   RangeStr=':';
   for nd=2:numdims
         RangeStr=[RangeStr,',:'];
   end
end

IndC=strfind(RangeStr,',');% index of commas
if length(IndC)~=numdims-1
   disp(['Input dimension range is not correct, should be: ',num2str(numdims),'-d']);
   return
end

startstr=''; countstr=''; stridestr='';
for nn=1:length(IndC)+1
      if nn==1
         tmpstr=RangeStr(1:IndC(1)-1);
      elseif nn<numdims
         tmpstr=RangeStr(IndC(nn-1)+1:IndC(nn)-1);
      else
         tmpstr=RangeStr(IndC(nn-1)+1:end);
      end

      [tmpstart,tmpcount,tmpstride]=GetIndFromStr(tmpstr,':',dimlen(vardimids(numdims-nn+1)+1));
     if nn==1
        startstr=[num2str(tmpstart),'],'];
        countstr=[num2str(tmpcount),'],'];
        stridestr=[num2str(tmpstride),']'];
     elseif nn==numdims
        startstr=[',[',num2str(tmpstart),',',startstr];
        countstr=['[',num2str(tmpcount),',',countstr];
        stridestr=['[',num2str(tmpstride),',',stridestr];
     else
        startstr=[num2str(tmpstart),',',startstr];
        countstr=[num2str(tmpcount),',',countstr];
        stridestr=[num2str(tmpstride),',',stridestr];
     end
end

if IsDebug
   disp(['ncvardata=netcdf.getVar(ncfid,varid',startstr,countstr,stridestr,');']);
end
eval(['ncvardata=netcdf.getVar(ncfid,varid',startstr,countstr,stridestr,');']);
netcdf.close(ncfid);
ncvardata=permute(ncvardata,length(size(ncvardata)):-1:1);

function [numstart,numcount,numstride]=GetIndFromStr(tmpstr,ctag,Ndim)
% Read the numbers from the special string
IsDebug=0;
IndC=strfind(tmpstr,ctag);
if isempty(IndC)
   numstart=str2double(tmpstr)-1;
   numcount=1;
   numstride=1;
else
switch length(IndC)
    case {1}
        switch IndC
            case {1} % : and :num
                if strcmp(tmpstr,':')
                   numstart=0; numcount=Ndim; numstride=1;
                else
                   if strcmp(tmpstr(2:end),'end')
                      numstart=0; numcount=Ndim; numstride=1;
                   else
                      numstart=0; numcount=str2double(tmpstr(2:end))-1; numstride=1;
                   end
                end
            case {length(tmpstr)}
                if strcmp(tmpstr,':')
                    numstart=0; numcount=Ndim; numstride=1;
                    return
                else
                    numstart=str2double(tmpstr(1:IndC-1))-1;
                    numcount=Ndim-numstart;
                    numstride=1;
                end
           otherwise
                numstart=str2double(tmpstr(1:IndC-1))-1;
                if strcmp(tmpstr(IndC+1:end),'end')
                    numend=Ndim;
                else
                    numend=str2double(tmpstr(IndC+1:end));
                end
                numcount=numend-numstart;
                numstride=1;
            end
   case {2}
      % num0:stride:num1
      if IndC(1)==1
         numstart=0;
      else
         numstart=str2double(tmpstr(1:IndC(1)-1))-1;
      end
      if IndC(2)==IndC(1)+1
         numstride=1;
      else
         numstride=str2double(tmpstr(IndC(1)+1:IndC(2)-1));
      end
      if IndC(2)==length(tmpstr)
             numend=Ndim;
      else
         if strcmp(tmpstr(IndC(2)+1:end),'end')
            numend=Ndim;
         else
            numend=str2double(tmpstr(IndC(2)+1:end));
         end
      end
      numcount=numend-numstart;
   otherwise
       error('Not defined range type')
   end
end
if IsDebug
   disp(['tmpstr=',tmpstr])
   disp(['start:',num2str(numstart), ' stride:',num2str(numstride),' count:',num2str(numcount)])
end

script demo

Wednesday, December 22, 2010

read netcdf file using native matlab functions

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