Import or Export a Sequence of Files

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Luca Fenech 2021-2-27

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/757974-import-or-export-a-sequence-of-files

评论： Luca Fenech 2021-3-18

I have been trying to export photos on MATLAB. With a.bmp, b.bmp and c.bmp works perfectly, but wrting *.bmp gives me an error. Could you help me out please.

Thanks

clc; clear all;
% paths = fullfile('c:\','users','fenec','Desktop','Cam_1',{'a.bmp'; 'b.bmp'; 'c.bmp'});
paths = dir(fullfile('c:\','users','fenec','Desktop','Cam_1','*.bmp'));
for R = 1:length(paths)
    temp = char(paths(R));
    I = imread(temp);
    figure;
    imshow(I, []);
end

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Stephen23 2021-2-27

在 MATLAB Online 中打开

I don't see how this approach would ever work without error:

S = dir();
char(S(1))
Error using char
Conversion to char from struct is not possible.

Most likely you would be much better off just using the standard approach of using indexing and fieldname to access the structure content (just as they were designed for):

https://www.mathworks.com/help/matlab/matlab_prog/access-multiple-elements-of-a-nonscalar-struct-array.html

Luca Fenech 2021-2-27

在 MATLAB Online 中打开

Thats why I got confused. Since when uncommenting the 2nd line:

clc; clear all;
paths = fullfile('c:\','users','fenec','Desktop','Cam_1',{'a.bmp'; 'b.bmp'; 'c.bmp'});
% paths = dir(fullfile('c:\','users','fenec','Desktop','Cam_1','*.bmp'));
for R = 1:length(paths)
    temp = char(paths(R));
    I = imread(temp);
    figure;
    imshow(I, []);
end

Like the above code works perfectly.

The problem when came when I wanted to be more generic, by having

'*.bmp'

Thanks for link provided.

Moreover, the answer and explanation to this query can be found here:

https://www.mathworks.com/matlabcentral/answers/757974-import-or-export-a-sequence-of-files#answer_635024

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Answer 1

Cris LaPierre 2021-2-27

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/757974-import-or-export-a-sequence-of-files#answer_635024

在 MATLAB Online 中打开

Perhaps the issue is that paths is a structure containing several fields and not just the path. Look at the dir documentation page for more.

The fields are

name
folder
date
bytes
isdir
datenum

See explanations here.

Perhaps modify your code to be

for R = 1:length(paths)
    temp = fullfile(paths(R).folder,paths(R).name);
    I = imread(temp);
    figure;
    imshow(I, []);
end

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Stephen23 2021-3-18

编辑：Stephen23 2021-3-18

在 MATLAB Online 中打开

@Luca Fenech: download, unzip, and use NATSORTFILES (following its documentation of course):

https://www.mathworks.com/matlabcentral/fileexchange/47434-natural-order-filename-sort

For example:

P = fullfile('C:\','users','fenec','Desktop','Cam 1');
S = dir(fullfile(P,'*.bmp'));
C = natsortfiles({S.name}); % sort filenames alphanumerically.
for k = 1:numel(C)
    F = fullfile(P,C{k});
    I = imread(F);
    figure;
    imshow(I,[]);
end

You can also sort the structure S by using the second output from NATOSRTFILES, which is the sort index.

Luca Fenech 2021-3-18

@Stephen Cobeldick... this worked perfectly.

I really appreciate for your help. Thanks a lot.

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