RE: automated text file reading and array element extraction

[William Krekeler]

 

files=dir('*.txt');  %creates struct with all files

filesarray = struct2cell(files); %converts struct array to cell array

names=filesarray(1,:)   %extracts first row of cell array (all file names) and assigns to names

 

for i=1:length(names)

eval([ sprintf( ' files(%d).array = load( files(%d).name, ''-ascii'');',i,i) ] )

end

 

X = struct2vec( files(:).array );

Xreduce = X( :, [2:2:size(X,2)] ); % only column 2 data from each file

 

 

Use the following function to convert to a matrix.

 

 

function [X] = struct2vec(varargin)

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% function [X] = struct2vec(varargin)

%  Author:     William Krekeler

%  Date  :     20070713

%  version:    1

%  Synopsis:   convert structure array to a multidimensional matrix

%

%  Returns:   matrix x

%

%  Variables:

%             X = data vector

%  References:

%  See also:

%  Additional Notes:

%              this code is useful for converting APMReadData output

%  Example Call:

%        DPATH = 'C:\some_path';

%        DFILE0='some_data.txt';

%        data0 = readYourDataProprietary(fullfile(DPATH,DFILE0));

%        x = struct2vec(data0.structureArray);

%        plot(x);

%  Copyright William Krekeler 2010, you may distribute and modify, you may not charge for or close source this code without my explicit permission.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

 

X = cell2mat(varargin);

 

 

Bill Krekeler
Electro-Optics Engineer
CET, LLC
address@hidden

 

From: Michael Hadrien [mailto:address@hidden
Sent: Thursday, December 02, 2010 7:11 PM
To: Octave
Subject: automated text file reading and array element extraction

 

Hello eveyone, 

 

I'm a beginner in Octave, running Octave 3.2.4 on Ubuntu 10.10. 

What I'm trying to do is read numerical data in sequentially named text files in two different directories, extract the second column from each file in both directories, subtract all the columns in one directory from all the columns in the other directory, then create a new directory with a set of files containing the first column (from any directory, they're constants) and the resulting columns from the subtraction. 

 

So Directory A has:

aaa_001.txt

aaa_002.txt

aaa_003.txt

 

Directory B has: 

bbb_001.txt

bbb_002.txt

bbb_003.txt

 

The files all look like this:

33  32

48  45

76  34

46  54

 

The first column never changes. 

I want to take second columns from one directory and subtract them from all the second columns in the other directory. Both directories have the same number of files. 

 

This is the code I currently have:

 

files=dir('*.txt'); #creates struct with all files

filesarray = struct2cell(files); #converts struct array to cell array

names=filesarray(1,:) #extracts first row of cell array (where all the file names) and assigns to names

 

for i=1:length(names)

eval(['load ' files(i).name ' -ascii'])

end

 

 

I've repeated this for both directories. Now all the files have been loaded and I can extract column 2 from each file individually using:

 

aaa_001(:,2)

 

But I want to be able to do this for all the files automatically and do the subtraction operations. 

I'm not sure what to search or how to go about this. I've thought of maybe creating two matrices with all the col 2 data from each directory on a different matrix, but I don't know how to do that. Then I'd be able to subtract the matrices. The next step would be extracting and writing each column to a new text file.

 

Any help I can get would be greatly appreciated!

 

I've attached example files (files beginning with aaa go in one directory and those beginning with bbb go in another).

 

Thank you!

 

--Michael