constructing file identifier from string?

Question

Joseph Koval 2018-7-16

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/410472-constructing-file-identifier-from-string

回答： KSSV 2018-7-16

I open several files, write text to the files upon opening them...for example...

fullfileKBDR = strcat('/Users/jkoval/Documents/MATLAB/archived_fod_forecasts/output/KBDR_',forecastyears(k,:),'.csv')
    fileID1 = fopen(fullfileKBDR, 'w')
    fprintf(fileID1,formatSpec)
      fullfileKMHT = strcat('/Users/jkoval/Documents/MATLAB/archived_fod_forecasts/output/KMHT_',forecastyears(k,:),'.csv')
      fileID2 = fopen(fullfileKMHT, 'w');
      fprintf(fileID2,formatSpec)
      fullfileKASH = strcat('/Users/jkoval/Documents/MATLAB/archived_fod_forecasts/output/KASH_',forecastyears(k,:),'.csv')
      fileID3 = fopen(fullfileKASH, 'w');
      fprintf(fileID3,formatSpec)
      fullfileKPWM = strcat('/Users/jkoval/Documents/MATLAB/archived_fod_forecasts/output/KPWM_',forecastyears(k,:),'.csv')
      fileID4 = fopen(fullfileKPWM, 'w');
      fprintf(fileID4,formatSpec)

But the question is that later in the code, I have a loop where I'm processing data in the loop. I want to be able to construct the file identifier (e.g. fileID1, fileID2, fileID3, fileID4) and write to the file based on the loop counter. So something that would like this, but it doesn't work:

for n = 1:4
            %Do stuff
            nasstr = string(n)
            fileident = strcat('fileID',nasstr)
            fprintf(fileident, 'blah\n')
          end

Can someone share the syntax that would make this work? Thanks.

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Answer 1

KSSV 2018-7-16

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/410472-constructing-file-identifier-from-string#answer_328941

在 MATLAB Online 中打开

You can initialize file identifiers as an array, and use them in loop.

fullfileKBDR = strcat('/Users/jkoval/Documents/MATLAB/archived_fod_forecasts/output/KBDR_','.csv')
fid(1) = fopen(fullfileKBDR, 'w')
fprintf(fileID1,formatSpec)
fullfileKMHT = strcat('/Users/jkoval/Documents/MATLAB/archived_fod_forecasts/output/KMHT_','.csv')
fid(2) = fopen(fullfileKMHT, 'w');
fprintf(fileID2,formatSpec)
fullfileKASH = strcat('/Users/jkoval/Documents/MATLAB/archived_fod_forecasts/output/KASH_','.csv')
fid(3) = fopen(fullfileKASH, 'w');
fprintf(fileID3,formatSpec)
fullfileKPWM = strcat('/Users/jkoval/Documents/MATLAB/archived_fod_forecasts/output/KPWM_','.csv')
fid(4) = fopen(fullfileKPWM, 'w');
fprintf(fileID4,formatSpec)
for n = 1:4
    %Do stuff
    nasstr = string(n)
    fid(n)   % this gives file identifier 
end