load a file and sort out bad data.

Question

Adam 2014-6-16

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/134706-load-a-file-and-sort-out-bad-data

编辑： Jason Nicholson 2014-6-17

I have a text file like shown below, that I want to load in to matlab. The format of the file should be like: [temp rate type], but if some of the data is not in correct format i want them sorted out. For example a file could look like this:

0.109 1
corrupted line
0.096 2
0 3
0.517 3
0.8 5
1.086 4
3
0.934 2
3 3 3 3 3
0.109 1
0.100 1
0.100 2
0.600 3
0.850 5
1.080 4
0.950 2
0.110 1

Any letters and lines that are not in correct format ( 3 numbers per line) should be ignored, when loading the file. How can I do this? I have tried different combinations of fgetl(), scanf(), and textscan(), but I am not sure how to do it. Please help me if you can.

Adam

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Answer 1

Jason Nicholson 2014-6-16

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/134706-load-a-file-and-sort-out-bad-data#answer_141269

编辑：Jason Nicholson 2014-6-17

在 MATLAB Online 中打开

parse.m

You should use the lower level fgetl which gets one line at a time as a string. You can then parse that line in a while loop.

Use this code or the m file attached to parse the data you listed in your post.

 % adjust this if you know the maximum array size in advance
  bufferSize = 1e4;
  data = zeros(bufferSize, 3);
% use this for more flexibility
%DELIMITERS = '\t , ;'; % this is tab, space, comma, or semicolon as delimiter
numberOfGoodLinesSaved = 0;
fileID = fopen('data.txt', 'r');
testForNextLine = ~feof(fileID);
while (testForNextLine )
currentLine = fgetl(fileID);
  % parse current line
  currentLineNumerical = sscanf(currentLine, '%f');
  % use this line instead if you need the DELIMITER to vary or you want
  % more flexibility
  % currentLineNumerical = sscanf(currentLine, ['%f%*[' DELIMITERS ']');
  % check if current line is valid
  if ~isempty(currentLineNumerical) && numel(currentLineNumerical) == 3
      numberOfGoodLinesSaved = numberOfGoodLinesSaved + 1;
      data(numberOfGoodLinesSaved,:) = currentLineNumerical;
  else
      % do nothing
  end
  % check buffer size is big enough.  double the buffer size if needed
  if numberOfGoodLinesSaved == bufferSize
      bufferSize = 2*bufferSize;
      data(numberOfGoodLinesSaved+1:bufferSize,:) = 0;
  end
  testForNextLine = ~feof(fileID);
end % end while loop
% delete extra lines in buffer
data(numberOfGoodLinesSaved+1:end,:) = [];
fclose(fileID);