Find strings within other strings then pull data from that point

Question

A-Rod 2024-8-19

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2146359-find-strings-within-other-strings-then-pull-data-from-that-point

评论： Voss 2024-8-20

采纳的回答： Voss

P0300.txt

在 MATLAB Online 中打开

dear collegaes, please let me ask your help to find a solution for my data analisys.

I have a P0300.txt file that contains a long strip.

here is a portion of P0300.txt:

59 04 03 01 00 65 01 3E 51 09 00 00 51 1C 00 E1

I need to find sets of data, sets could be 2 or 4 digits.

lets say I need to find 01 3E

DATA = regexp(fileread('P0300.txt'), '\r?\n', 'split')'; 
>> A = string(DATA); 
>> B = strfind(A,'01 3E');

B gives me the position where 01 3E is, in this case B = 19

after this I need to extract the 6 digits on the rigth 51 09 00 <-- this values can change depend on test conditions

Any idea on how can I do that?

your feedback will be highly appreciated

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Answer 1

Voss 2024-8-19

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https://ww2.mathworks.cn/matlabcentral/answers/2146359-find-strings-within-other-strings-then-pull-data-from-that-point#answer_1501034

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filename = 'P0300.txt';
to_find = '01 3E';
str = fileread(filename);
pat = strjoin(repmat({'[\dA-F]{2}'},1,3),' ');
C = regexp(str,[to_find ' (' pat ')'],'tokens');
C = [C{:}]
C = 1x1 cell array
    {'51 09 00'}

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A-Rod 2024-8-20

编辑：A-Rod 2024-8-20

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update:

what if the output is and odd number?

to_find = { ...

'E1 54', 3; ...

'01 3E', 5; ...

'51 09', 4; ...

};

I tried to update my self but it's giving me ahard time, please help me here one more time.

filename = 'P0300.txt';
% now to_find is a cell array with two columns; the first column is
% the character vector to find, and the second column is the number 
% of digits to grab afterward (the number of digits must be even)
to_find = { ...
    'E1 54', 3; ... 
    '01 3E', 5; ... 
    '51 09', 4; ... 
    };
str = fileread(filename);
N = size(to_find,1);
results = cell(N,1);
for ii = 1:N
   
    a = to_find(:,2);
    b = cell2mat(a);
    idx = rem(b,2) == 0   
    if idx(N) == 1
        pat = strjoin(repmat({'[\dA-F]{2}'},1,to_find{ii,2}/2),' ');
        C = regexp(str,[to_find{ii,1} ' (' pat ')'],'tokens');
        results{ii} = [C{:}];
    else
        pat = strjoin(repmat({'[\dA-F]{2}'},1,to_find{ii,2}/1),' ');
        C = regexp(str,[to_find{ii,1} ' (' pat ')'],'tokens');
        results{ii} = [C{:}];
end
end

A-Rod 2024-8-20

移动：Voss 2024-8-20

it saved my day!! you're the best thanks a lot

Voss 2024-8-20

You're welcome!

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Answer 2

Animesh 2024-8-19

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https://ww2.mathworks.cn/matlabcentral/answers/2146359-find-strings-within-other-strings-then-pull-data-from-that-point#answer_1501024

编辑：Animesh 2024-8-19

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Hey @A-Rod,

To extract 6 digits following a specific pattern in your text file, you can utilize MATLAB's string manupilation functions such as 'regexp'.

Here is a sample MATLAB script to achieve the same:

fileContent = fileread('P0300.txt');
pattern = '01 3E';
% Use regular expression to find the pattern and extract the following 6 digits
expression = [pattern, '\s+([\dA-F]{2}\s+[\dA-F]{2}\s+[\dA-F]{2})'];
match = regexp(fileContent, expression, 'tokens');
% Check if any match is found
if ~isempty(match)
    % Extract the first match (if multiple matches are found)
    extractedDigits = match{1}{1};
    fprintf('Extracted digits: %s\n', extractedDigits);
else
    fprintf('Pattern not found in the file.\n');
end
Extracted digits: 51 09 00

You can refer the following MathWorks documentation for more information:

https://www.mathworks.com/help/matlab/ref/regexp.html

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A-Rod 2024-8-19

Thank you for taking time to asnwer my question, this code does the job.

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Answer 3

Matt J 2024-8-19

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https://ww2.mathworks.cn/matlabcentral/answers/2146359-find-strings-within-other-strings-then-pull-data-from-that-point#answer_1501029

编辑：Matt J 2024-8-19

在 MATLAB Online 中打开

fileContent = fileread('P0300.txt');
prefix="01 3E";
e=" "+digitsPattern(2);
pattern = prefix+e+e+e;
matches = extractAfter( extract(fileContent,pattern), prefix);