How to make a CSV parser for multiple files with different names?

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Micard 2015-11-30

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https://ww2.mathworks.cn/matlabcentral/answers/258152-how-to-make-a-csv-parser-for-multiple-files-with-different-names

评论： Walter Roberson 2015-11-30

I am trying to make a parser of multiple CSV files here. Here's a solution for one. This allows me to pick one of the files and work with it. All I want to do with each file is to find the maximum value with respect to other columns. For example, here's the example of output I get:

function upload_btn_Callback(~, ~, handles)
%Uploading a file via user interface
uploaded_file = uigetfile('*.csv','Select a .csv data file');
%If file is loaded
if uploaded_file == 0
    set(handles.upload_txt, 'String', 'Status: Cancelled');
else
    set(handles.upload_txt, 'String', 'Status: Please wait...');
      %Loading the array with CSV-file values
      array = csvread(uploaded_file, 8, 0);
      set(handles.upload_txt, 'String', ['Uploaded: ' uploaded_file]);
      format long;
      %Finding all max velocity values
      max_vel = max(array(:, 5));
      idx = find(array(:, 5) == max_vel);
      %Finding time of the max velocity values
      t = array(idx(:, 1), 3);
      time = num2str(t);
      %Finding altitude of the max velocity values
      a = array(idx(:,1), 4);
      alt = num2str(a);
      set(handles.uitable1, 'Visible', 'on');
      set(handles.pushbutton2, 'Visible', 'on');
      set(handles.uitable1, 'Data', {num2str(max_vel), alt, time});
      %This doesn't work...
      plot(array(:, 3), array(:, 5));
  end

With all this I can't figure out how to make it work for multiple files. Ultimately all I need to do is to pick a directory with those files and load all files with .csv extension, no matter what their names are. I tried different ways with dir() and other stuff but none would work... Maybe there's a better way to do, other than this? I honestly wouldn't even do it in MATLAB if it weren't for its speed with matrices. (Files are hundreds of megabytes big).

Thank you!

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Answer 1

Walter Roberson 2015-11-30

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/258152-how-to-make-a-csv-parser-for-multiple-files-with-different-names#answer_201598

http://matlab.wikia.com/wiki/FAQ#How_can_I_process_a_sequence_of_files.3F

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Walter Roberson 2015-11-30

在 MATLAB Online 中打开

folder = uigetdir('What folder do you want?');
dirinfo = dir(fullfile(folder, '*.csv'));
for K = 1 : length(dirinfo)
  uploaded_file = fullfile(folder, dirinfo(K).name);
  array = csvread(uploaded_file, 8, 0);
  ... etc etc...
end

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Answer 2

Micard 2015-11-30

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/258152-how-to-make-a-csv-parser-for-multiple-files-with-different-names#answer_201602

I have seen that, and this does not help me in my situation. I need to use User Interface to locate a specific folder and use ALL the files in that directory (i.e. I don't want the user to pick all the files manually). In addition, the process described in that example cannot be merged (implemented) with my code, at least not the way I tried.