Trouble reading in formatted text file

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Jenny May 2016-6-21

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/291375-trouble-reading-in-formatted-text-file

编辑： Shameer Parmar 2016-6-22

Hi, I am trying to read in a formatted text file of unknown size. An example of the data I want to read in is shown below:

*lines 1-3: blank
*lines 4-6: useless text
*line 7: string string string double  %(this line should be read into Settings) 
*line 8: useless text
*lines 9-12: string double double string %(this line should be read into AlarmData)
*lines 13-16: blank
*line 17: string string %(this line should be read into Time)

This pattern then repeats throughout the entire file. My first thought was to determine the number of lines in the file so I used this code:

 FileID= fopen(filename);
%Code to find number of lines in the file
assert(FileID~= -1, 'Could not read: %s', filename);
x= onCleanup(@() fclose(FileID));
count=0;
while ~feof(FileID)
    count= count+sum(fread( FileID, 16384, 'char')==char(10));
end
fclose(FileID)
%code to determine number of data runs
num_data_runs=count/17;

I then try to loop through the file with textscan commands to read in the data to appropriate cells

    FileID= fopen(filename);
    iter=1;
      while(iter<=num_data_runs)
          Settings(iter,1:4)= textscan(FileID, '%s%s%s%f',1, 'headerLines', 6);
          AlarmData(iter,1:4)= textscan(FileID, '%s %f %f %s',4, 'headerLines', 2);
          Time(iter,1:2)= textscan(FileID, '%s%s', 1, 'headerLines', 4);
          iter=iter+1;
      end
      fclose(FileID)

The result of this code is a 3x4 cell of AlarmData, a 3x4 cell of Settings, and a 3x2 cell of Time. The first row in all of these cells is what I intended them to be, but the other rows are all containing the wrong data from the file. Any thoughts?

Thanks

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Answer 1

Shameer Parmar 2016-6-21

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/291375-trouble-reading-in-formatted-text-file#answer_226192

在 MATLAB Online 中打开

Consider you have text file with name 'Data.txt'.. then

Following command will give you all data present in text file.

Data = textread('Data.txt', '%s', 'delimiter', '')

and then..

NumberOfRows = length(Data);

to read the data row wise..

 for count = 1:NumberOfRows
     RowData = Data{count};
     % add logic to perform any action on RowData.
 end

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Jenny May 2016-6-21

Ah, thank you. I don't know why I tried using a more complicated method. Will this code still work fairly quickly if my text file is thousands of lines long?

Shameer Parmar 2016-6-22