Manipulate numbers in existing txt file

Question

Stefan 2017-12-18

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评论： Stefan 2017-12-19

采纳的回答： Walter Roberson

Hi,

I want to manipulate numbers in a txt file which was created by catia. The txt file looks like this:

Catia puts a space between every string and float. For example I want to change 'l_overall (mm)' to 5000.

Thank you for your help!

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Walter Roberson 2017-12-18

I notice that there is a space between l_overall and (mm) and a space between w_overall and (mm) but no space between h_overall and (mm) . Is the actual file consistent about the space there or not?

Can we assume that the variables are always in exactly the same order and that we can assume that l_overall will be the first entry on the line (for example) ? Or is it necessary to match the strings to determine which column to make the change to ?

Is it possible that the fields are really tab delimited rather than space delimited ?

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Answer 1

Walter Roberson 2017-12-19

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https://ww2.mathworks.cn/matlabcentral/answers/373462-manipulate-numbers-in-existing-txt-file#answer_296847

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fid = fopen('Table1.txt', 'rt');
colnames = fgetl(fid);
colvals = fscanf(fid, '%f', [1 inf]);
fclose(fid)
colvals(1) = 5000;
fid = fopen('newTable1.txt', 'wt');
fprintf(fid, '%s\n', colnames);
fprintf(fid, '%g\t', colvals(1:end-1));
fprintf(fid, '%g\n', colvals(end));
fclose(fid)

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Stefan 2017-12-19

Thank you very much! I found my mistake.

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Answer 2

YT 2017-12-18

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https://ww2.mathworks.cn/matlabcentral/answers/373462-manipulate-numbers-in-existing-txt-file#answer_296714

在 MATLAB Online 中打开

test.txt

I don't know if I understand the question correctly, but if you want to change 'l_overall (mm)' to '5000' in your text file, you can do something like this (I assumed that your text file looks something like the test.txt I attached)

clear all;
fileID = fopen('test.txt');
C = textscan(fileID,'%s','delimiter','\n');
fclose(fileID);
C{:} = strrep(C{:},'l_overall (mm)','5000'); %replacing 'l_overall (mm)' by '5000'
writetable(cell2table(C{:}),'updated_data.txt','WriteVariableNames',0) %writing the new data