get_gridsize

 PURPOSE:  read the size of an (ESRI) ASCII grid from the header information
           without loading the data, eg. for preallocating memory.
 -------------------------------------------------------------------
 USAGE: [rows, cols] = get_gridsize(file)
 where: 
        [file] filename (incl path) of the ASCII grid.
 -------------------------------------------------------------------------
 OUTPUTS:
        [rows, cols] are the rows and columns as given in the header file 
        
 -------------------------------------------------------------------
 NOTES: Currently only supports ESRIs ASCII grid format header. 
        Designed to read import grid size for preallocating memory.

 SEE ALSO: asciigrid2mat, hdrload

0001 function [rows, cols] = get_gridsize(file)
0002 % PURPOSE:  read the size of an (ESRI) ASCII grid from the header information
0003 %           without loading the data, eg. for preallocating memory.
0004 % -------------------------------------------------------------------
0005 % USAGE: [rows, cols] = get_gridsize(file)
0006 % where:
0007 %        [file] filename (incl path) of the ASCII grid.
0008 % -------------------------------------------------------------------------
0009 % OUTPUTS:
0010 %        [rows, cols] are the rows and columns as given in the header file
0011 %
0012 % -------------------------------------------------------------------
0013 % NOTES: Currently only supports ESRIs ASCII grid format header.
0014 %        Designed to read import grid size for preallocating memory.
0015 %
0016 % SEE ALSO: asciigrid2mat, hdrload
0017 
0018 % Felix Hebeler, Geography Dept., University Zurich, March 2006.
0019 
0020 %% parameter
0021 hdrlines=2; %ascii grid has 6 header lines, but we only need the first 2
0022 
0023 %% check number and type of arguments
0024 if nargin < 1
0025   error('Function requires one input argument');
0026 elseif ~ischar(file)
0027   error('Input argument must be a string representing a filename');
0028 end
0029 
0030 %% Open the file
0031 fid = fopen(file);
0032 if fid==-1
0033   error('File not found or permission denied');
0034 end
0035 
0036 max_line = 0;
0037 
0038 %% Start processing.
0039 line = fgetl(fid);
0040 if ~ischar(line)
0041   disp('Warning: file contains no header and no data')
0042 end;
0043 
0044 
0045 %% We loop through the file for the first [hdrlines] lines
0046 for no_lines=1:hdrlines
0047   max_line = max([max_line, length(line)]);
0048   eval(['line', num2str(no_lines), '=line;']);
0049   line = fgetl(fid);
0050 end 
0051 % and close it again
0052 fclose(fid);
0053 
0054 %% parse the info from the first two lines
0055 % only works for ESRI ascii headers
0056 cols=str2num(line1(strfind(line1,' ')+1:end));
0057 rows=str2num(line2(strfind(line1,' ')+1:end));