MATLAB: Extracting numerical results from a text file at different positions

column vectorCurve Fitting ToolboxMATLABposition;read text

I have a number of output files to process, written out from Finite Element Analysis software, from which I need to extract data.

I need to extract data under 2 different "headings" from each of the files. However, each of the files has these headings at different rows. I have attached a "zipped" file with 2 files indicating this problem.

The following screenshots show the "headings" highlighted and the numerical data to be extracted, shown inside a "box":

First Heading

Second Heading

I have tried a number of options in Matlab, but I am overwhelmed as I am new to Matlab and programming.

Any assistance and guidance, would be much appreciated.

Best Answer

good catch, my bad:) it was late at night. This should work. In either case if you are learning MATLAB, regexp are very powerful. They exist in many languages, it is worth understanding them:)

a = fileread('0295_PhD_AB~Analysis 1.txt');
% find ( H A R M O N I C =    \d )
[b,c] = regexp(a,'( H A R M O N I C =    \d )','tokens');
result = table();
% find the 2nd and the 6th number in the table
for i = 1:length(c)
    aux = (a(c(i)+586:c(i)+700));
    d = regexp(aux,'([0-9.E-+]*)','tokens');
    result = [result;table(repmat(b{i},2,1),[d{2};d{6}])];
end
result.Var2 = str2double(result.Var2);

Related Solutions

MATLAB: Extracting values by looping through multiple files

displ=[];                                     % empty displacement array...
d=dir('*.out');
for i=1:numel(d)
  txt=fileread(d(i).name);                    % read file in turn...see previous note on ordering...
  txt=split(txt,{[char(13) char(10)]});       % turn into cellstr array for line indexing instead of character
  % return the displacement data--this returns node as well as all directional in case may want later...
  ix=find(contains(txt,'( H A R M O N I C =  '));  % find the interesting section
  for i = 1:length(ix)
    displ=[displ; cell2mat(textscan(char(txt(ix(1)+[18:19].')).',repmat('%f',1,4)))];
  end
end
% operate on resulting displacement array here...
...

MATLAB: Importing specific rows of Data from Text file

If the entire file fits in memory, try this code

    >> num = cssm()
    num =
             0   60.2750   -0.1577   -0.0069         0
             0   60.2750   -0.1577   -0.0069         0
             0   60.2750   -0.1577   -0.0069         0
             0   60.2750   -0.1577   -0.0069         0

where

    function    out = cssm()
        %   read the entire file to one cell array with one row per cell
        fid = fopen( 'cssm.txt', 'r' );
        cac = textscan( fid, '%s', 'Delimiter', '\n' );
        [~] = fclose( fid );
        %   find rows which begin with 'R'.  
        isR = cellfun( @(str) strncmp(strtrim(str),'R',1), cac{:} );
        %   extract the rows beginning with 'R' 
        rlt = cac{:}(isR);
        %   join all rows with results to one long string separated by '\n'
        one_str = strjoin( rlt, '\n' );
        %   parse the string. 

        result  = textscan( one_str, '%c%f%f%f%f%f', 'CollectOutput',true ); 
        %   make sure that only results are included in the output

        assert( strcmp( unique(result{1}), 'R' )     ...
            ,   'Non-result rows included in result' )
        out = result{2};
    end

and where cssm.txt contains

    C 0 6.026 0.34 24.12 4.28 -100.00 -100.00
    C 0 7.030 -0.46 24.09 8.37 -100.00 -100.00
    C 0 8.034 -0.23 24.09 7.50 -100.00 -100.00
    R 0 60.275 -0.157674 -0.006891 0.000000
    C 0 6.026 0.34 24.12 4.28 -100.00 -100.00
    C 0 7.030 -0.46 24.09 8.37 -100.00 -100.00
    C 0 8.034 -0.23 24.09 7.50 -100.00 -100.00
    R 0 60.275 -0.157674 -0.006891 0.000000
    C 0 6.026 0.34 24.12 4.28 -100.00 -100.00
    C 0 7.030 -0.46 24.09 8.37 -100.00 -100.00
    C 0 8.034 -0.23 24.09 7.50 -100.00 -100.00
    R 0 60.275 -0.157674 -0.006891 0.000000
    C 0 6.026 0.34 24.12 4.28 -100.00 -100.00
    C 0 7.030 -0.46 24.09 8.37 -100.00 -100.00
    C 0 8.034 -0.23 24.09 7.50 -100.00 -100.00
    R 0 60.275 -0.157674 -0.006891 0.000000

&nbsp

... and an alternative, which is an order of magnitude faster

    function    out = faster()
        %   read the entire file to one string
        str = fileread( 'cssm.txt' );
        %   find start and end indicies of all the "rows" beginning with 'R'
        xpr = '(?<=\s)R[^(\n|\r)]+(\n|\r){1,2}';
        [ix1,ix2] = regexp( str, xpr, 'start', 'end' );
        %   extract the "rows" beginning with 'R'
        isi = false(1,length(str)); 
        for ii = 1:length(ix1)
            isi(ix1(ii):ix2(ii))=true; 
        end
        one_str = str(isi);
        %   parse the string. 
        result  = textscan( one_str, '%c%f%f%f%f%f', 'CollectOutput',true ); 
        %   make sure that only results are included in the output
        assert( strcmp( unique(result{1}), 'R' )     ...
            ,   'Non-result rows included in result' )
        out = result{2};
    end

Best Answer

Related Solutions

MATLAB: Extracting values by looping through multiple files

MATLAB: Importing specific rows of Data from Text file

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