Extract column from text file

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Suuz HMS 2023-6-12

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https://ww2.mathworks.cn/matlabcentral/answers/1981804-extract-column-from-text-file

评论： Suuz HMS 2023-6-13

Hi, for my research project I have to analyze a certain output. The output gives a lot of measurements (also a lot of data I don't need), but I don't know how to extract the specific column of data that I do need. The data looks like this:

P1,R0,14:17:36.779,47,0.01421266,[-0.03077913; 0.3226232; -0.4286367],[0; 0; 0],[-0.4424625; 0.120887; -0.9627059],[-0.03836464; 0.5967162; 0.3170188],[-6.699989; -7.350024; 5.199996],50.48101,0.7456555,0,0,0,-5.2,0

P0,R0,14:17:36.823,47,0.01403595,[-0.03077913; 0.3226232; -0.4286367],[0; 0; 0],[-0.4424625; 0.120887; -0.9627059],[-0.03836464; 0.5967162; 0.3170188],[-6.699989; -7.350024; 5.199996],50.48101,0.7456555,0.08738,0.6293842,17.97661,-5.2,0

But I only need the first number between brackets (value -0.03077913 here). How do I do this?

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the cyclist 2023-6-12

The best method will depend on exactly what format of file you have. (For example, is it Excel, a CSV, etc.?) Can you upload the file (using the paper clip icon from the INSERT area of the toolbar), or at least a few representative lines?

Suuz HMS 2023-6-13

Test1.2.txt

The file gets downloaded as a txt-file, but can also be saved as a .m file.

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Answer 1

Kautuk Raj 2023-6-13

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https://ww2.mathworks.cn/matlabcentral/answers/1981804-extract-column-from-text-file#answer_1254509

To extract the first number between the brackets in the data provided, we can use regular expressions in MATLAB.

This regular expression pattern \[([-0-9\.]+);([-0-9\.]+);([-0-9\.]+)\] will match the three numbers between the brackets and captures them in separate groups.

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Answer 2

Stephen23 2023-6-13

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https://ww2.mathworks.cn/matlabcentral/answers/1981804-extract-column-from-text-file#answer_1254519

在 MATLAB Online 中打开

Fake data (you would use FILEREAD):

S = sprintf('%s\n','P1,R0,14:17:36.779,47,0.01421266,[-0.03077913; 0.3226232; -0.4286367],[0; 0; 0],[-0.4424625; 0.120887; -0.9627059],[-0.03836464; 0.5967162; 0.3170188],[-6.699989; -7.350024; 5.199996],50.48101,0.7456555,0,0,0,-5.2,0','P0,R0,14:17:36.823,47,0.01403595,[-0.03077913; 0.3226232; -0.4286367],[0; 0; 0],[-0.4424625; 0.120887; -0.9627059],[-0.03836464; 0.5967162; 0.3170188],[-6.699989; -7.350024; 5.199996],50.48101,0.7456555,0.08738,0.6293842,17.97661,-5.2,0')
S = 
    'P1,R0,14:17:36.779,47,0.01421266,[-0.03077913; 0.3226232; -0.4286367],[0; 0; 0],[-0.4424625; 0.120887; -0.9627059],[-0.03836464; 0.5967162; 0.3170188],[-6.699989; -7.350024; 5.199996],50.48101,0.7456555,0,0,0,-5.2,0
     P0,R0,14:17:36.823,47,0.01403595,[-0.03077913; 0.3226232; -0.4286367],[0; 0; 0],[-0.4424625; 0.120887; -0.9627059],[-0.03836464; 0.5967162; 0.3170188],[-6.699989; -7.350024; 5.199996],50.48101,0.7456555,0.08738,0.6293842,17.97661,-5.2,0
     '
C = regexp(S,'(?<=\[)(-|+)?\d+\.?\d*','match')
C = 1×10 cell array
    {'-0.03077913'}    {'0'}    {'-0.4424625'}    {'-0.03836464'}    {'-6.699989'}    {'-0.03077913'}    {'0'}    {'-0.4424625'}    {'-0.03836464'}    {'-6.699989'}
V = str2double(C)
V = 1×10
   -0.0308         0   -0.4425   -0.0384   -6.7000   -0.0308         0   -0.4425   -0.0384   -6.7000