extract numbers or string after specific symbol from a text file

Question

Binu 2020-8-6

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https://ww2.mathworks.cn/matlabcentral/answers/575941-extract-numbers-or-string-after-specific-symbol-from-a-text-file

评论： Binu 2020-8-9

Hello

I have a set of text files with different attributes. Here is only three attributes of one file for example;

Location ID : 600
Field code : RNW
Sample interval : 60

The line number of these attributes are not the same for each file. How can I extract values after Location ID :, Field code :, and Sample interval : from all my text files if I put them in a loop.

Thank you

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Answer 1

Walter Roberson 2020-8-6

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https://ww2.mathworks.cn/matlabcentral/answers/575941-extract-numbers-or-string-after-specific-symbol-from-a-text-file#answer_475891

编辑：Walter Roberson 2020-8-6

dinfo = dir('*.txt');
nfiles = length(dinfo);
filenames = fullfile({dinfo.folder}, {dinfo.name});
IDs = cell(nfiles,1);
FCs = cell(nfiles,1);
intervals = cell(nfiles,1);
for K = 1 : nfiles
    
    filename = filenames{K};
    
    S = fileread(filename);
    parts = regexp(S, '(?<=Location ID\s*:\s*)(?<ID>\d+).*(?<=Field code\s*:\s*)(?<FC>\w+).*(?<=Sample interval\s*:\s*)(?<SI>\w+)', 'names');
    
    IDs{K} = str2double({parts.ID});
    FCs{K} = {parts.FC};
    intervals{K} = str2double({parts.SI});
end

Note: this code does not assume that there is only one occurance of the information per file. It will find all of the occurance in each file, provided that the parts are all in the same order and none of the parts are missing.

If there is only ever one occurance then the code could be simplified a little.

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Walter Roberson 2020-8-8

dinfo = dir('*.txt');
nfiles = length(dinfo);
filenames = fullfile({dinfo.folder}, {dinfo.name});
IDs = zeros(nfiles,1);
FCs = cell(nfiles,1);
intervals = zeros(nfiles,1);
for K = 1 : nfiles
    
    filename = filenames{K};
    
    S = fileread(filename);
    parts = regexp(S, '(?<=Location ID\s*:\s*)(?<ID>\d+).*(?<=Field code\s*:\s*)(?<FC>\w+).*(?<=Sample interval\s*:\s*)(?<SI>\w+)', 'names', 'once');
    
    IDs(K) = str2double(parts.ID);
    FCs{K} = parts.FC;
    intervals(K) = str2double(parts.SI);
end