% 07/2008
% David E. Haddad

% This is an efficient version of the script "three_column_utility.m" that
% is designed to clean very large datasets by loading a multi-column matrix from an
% existing text file and exporting two 3-column text files (one for ArcMap with a
% header, and another for P2G without a header).  Greater efficiency is achieved 
% by processing reducing the number of copies of the dataset in memory.  

% IMPORTANT NOTE: You cannot use MATLAB's "load" command if your original data text
% file has a header.  MAKE SURE YOU DELETE THE HEADER!

% Here we go...

clear all

% CHANGE THIS TO YOUR INPUT FILE NAME
xyz_data = load('input_filename.txt');


% For P2G (doesn't need a header):
dlmwrite('xyz_P2G.txt',xyz_data(:,1:3));  % comma delimited


% For ArcMap (needs a header):
fid = fopen('xyz_ArcMap.txt','w+t');
fprintf(fid,'x,y,z\n');  % writes headers to text file
fclose(fid);
dlmwrite('xyz_ArcMap.txt',xyz_data(:,1:3),'-append');  % comma delimited, 
                                                       % appends new xyz
                                                       % matrix to text file