Load files from relative path

Question

Sanjay Saini 2017-5-25

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/341843-load-files-from-relative-path

评论： Walter Roberson 2017-5-25

    function []= read_c3d_feat(output_list_relative)
        % rather than fileread, importdata save each line separetely.
        dir_list = importdata(output_list_relative);
        dim_feat = 512;
        for i = 1 : size(dir_list, 1)
            dir_str = char(dir_list(i));
            feat_files = dir([dir_str, '/*.res5b']);
            num_feat = length(feat_files);
            feat = zeros(num_feat, dim_feat);
            for j = 1 : num_feat
                feat_path = strcat(dir_str, '/', feat_files(j).name);
                [~, feat(j,:)] = read_binary_blob(feat_path);
            end

When i give input from command line like: read_c3d_feat('C:/Users/abc/Documents/MATLAB/features/0021.res5b')

Error using dir
Invalid path. The path must not contain a null character.
Error in read_c3d_feat (line 12)
        feat_files = dir([dir_str, '/*.res5b']);

And When i give input from command line like: read_c3d_feat('C:/Users/abc/Documents/MATLAB/features')

Error using importdata (line 226)
Unable to load file.
Use TEXTSCAN or FREAD for more complex formats.
Error in read_c3d_feat (line 6)
    dir_list = importdata(output_list_relative);
Caused by:
    Error using fread
    Invalid file identifier. Use fopen to generate a valid file identifier.

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Stephen23 2017-5-25

编辑：Stephen23 2017-5-25

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You question is unclear. In particular:

your title asks about relative paths, but your question and examples only show absolute paths.
you show examples where you call two different functions (once read_c3d_feat and once read_nvidia_c3d_feat), but you do not explain the difference, nor why you expect them to behave in the same way.
The first error message explains clearly that there is an invalid character in the string. Please place this code exactly before that line, and show us what it displays when the error occurs:

+[dir_str, '/*.res5b']

Sanjay Saini 2017-5-25

编辑：Sanjay Saini 2017-5-25

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Sorry Stephen Cobeldick, for my mistakes, however i have edit my question and i hope now it will give you more clarity in the question (about 1 and 2 point unclearness).

As you suggested in point 3 place the code "+[dir_str, '/*.res5b']" just before the line. I tried but its give again error like

read_c3d_feat('read_c3d_feat('C:/Users/abc/Documents/MATLAB/features/0021.res5b')

    Struct contents reference from a non-struct array object.
    Error in read_nvidia_c3d_feat (line 19)
                feat_path = strcat(dir_str, '/', feat_files(j).name);

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Answer 1

Walter Roberson 2017-5-25

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/341843-load-files-from-relative-path#answer_268337

在 MATLAB Online 中打开

You have not indicated what format C:/Users/abc/Documents/MATLAB/features/0021.res5b is in.

I can tell from the first situation that the first thing in the file is being interpreted as numeric 0. char() of numeric 0 is called "the null character" and it is not permitted in file names.

In the second situation, the problem is that it is not permitted to importdata() a directory name.

I suggest changing the importdata to

   dir_list = regexp( fileread( output_list_relative ), '\r?\n', 'split');
   dir_list( cellfun( @isempty, dir_list ) ) = [];       %remove empty lines

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Walter Roberson 2017-5-25

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finish up the routine IN THE INDICATED PLACES

The routine will then take as input a file name. The file will be opened, and every line in it will be expected to contain the name of a directory. If there is some other delimiter between the directory names, such as "," or ":", then the regexp() will need to be slightly changed.

Each directory named in the file will then be examined for res5b files, each of which will be processed by read_binary_blob.

You need to finish off the code having to do with what you do with the blobs once you read them in.

    function []= read_c3d_feat(output_list_relative)
      dir_list = regexp( fileread( output_list_relative ), '[\r\n]+', 'split');
      dir_list( cellfun( @isempty, dir_list ) ) = [];       %remove empty lines
        dim_feat = 512;
        for i = 1 : size(dir_list, 1)
            dir_str = dir_list{i};
            feat_files = dir( fullfile(dir_str, '*.res5b') );
            num_feat = length(feat_files);
            feat = zeros(num_feat, dim_feat);
            for j = 1 : num_feat
                feat_path = fullfile(dir_str, feat_files(j).name);
                [~, feat(j,:)] = read_binary_blob(feat_path);
            end
            FINISH YOUR "i" CODE HERE
          end          %of "for i"
       DO SOMETHING WITH THE RESULTS HERE
     end      %of function

Sanjay Saini 2017-5-25

在 MATLAB Online 中打开

I have finished the code as per below. But still same error.

 function []= read_c3d_feat(output_list_relative)
      dir_list = regexp( fileread( output_list_relative ), '[\r\n]+', 'split');
      dir_list( cellfun( @isempty, dir_list ) ) = [];       %remove empty lines
        dim_feat = 512;
        for i = 1 : size(dir_list, 1)
            dir_str = dir_list{i};
            feat_files = dir( fullfile(dir_str, '*.res5b') );
            num_feat = length(feat_files);
            feat = zeros(num_feat, dim_feat);
            for j = 1 : num_feat
                feat_path = fullfile(dir_str, feat_files(j).name);
                [~, feat(j,:)] = read_binary_blob(feat_path);
            end
        avg_feat = mean(feat, 1);
        avg_feat_double = double(avg_feat);
        fID = fopen(strcat(dir_str, '/c3d.res5b'), 'w');
        % libsvm requires that input data must be double
        fwrite(fID, avg_feat_double, 'double');
        fclose(fID);
    end
end

Error is: read_c3d_feat('C:/Users/abc/Documents/MATLAB/features')

Error using fileread (line 22) Could not open file C:/Users/abc/Documents/MATLAB/features. Is a directory.

Error in read_c3d_feat (line 2) dir_list = regexp( fileread( output_list_relative ), '[\r\n]+', 'split');

Sanjay Saini 2017-5-25

Thanks you so much Walter Roberson for your help. Actually i want to pass name of a directory that all *.res5b files are to be processed in. Anyway i will try to work on this, you take a good sleep.

Walter Roberson 2017-5-25

在 MATLAB Online 中打开

      function []= read_c3d_feat(dir_str)
        feat_files = dir( fullfile(dir_str, '*.res5b') );
        num_feat = length(feat_files);
        feat = zeros(num_feat, dim_feat);
        for j = 1 : num_feat
            feat_path = fullfile(dir_str, feat_files(j).name);
            [~, feat(j,:)] = read_binary_blob(feat_path);
        end
        avg_feat = mean(feat, 1);
        avg_feat_double = double(avg_feat);
        fID = fopen( fullfile(dir_str, 'c3d.res5b'), 'w');
        % libsvm requires that input data must be double
        fwrite(fID, avg_feat_double, 'double');
        fclose(fID);
    end

I would point out, however, that you are reading all of the *.res5b files in the directory and producing a *.res5b file in the same directory as output. That implies that if you were to run the code again on the same directory, that the c3d.res5b that you created last time would be read as input. Are you sure you want to write the output into the same directory, or are you should that you want it to be a .res5b file, or are you sure you do not want to ignore c3d.res5b when looking calculating the features ?

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