(Download image)

If I have a txt file, which contains the url that downloads images, how do we write the script to do that?

e.g. txt file information:

.. .. ...

Answer 1

[Walter Roberson]

projectdir = fullfile(pwd, 'saved_images');         %location to store the files
if ~exist(projectdir, 'dir')
   mkdir(projectdir);
end

fid = fopen('TheFile.txt', 'rt');

imcount = 0;
while true
  this_url = fgetl(fid);
  if ~ischar(this_url)
    break;        %end of file
  end
  if isempty(strtrim(this_url))
    continue      %empty line, probably near end of file
  end
  [url_path, url_img, url_ext] = fileparts(this_url);
  dest_file = fullfile(projectdir, [url_img url_ext]);
  if exist(dest_file, 'file')
    fprintf('skipping existing %s\n', dest_file);
    imcount = imcount + 1;
    urls{imcount} = this_url;
    img_files{imcount} = dest_file;
    %img_content{imcount} = imread(dest_file);
    continue;
  end
  fprintf('loading ... %s\n', url_img);
  try
    urlwrite(this_url, dest_file);
    imcount = imcount + 1;
    urls{imcount} = this_url;
    img_files{imcount} = dest_file;
    %img_content{imcount} = imread(dest_file);
  catch
    fprintf('failed downloading %s from "%s"\n', url_img, this_url);
  end
end

[matlabgeek]

Thank you very much for your code.

But, the speed to download the image is very slow, it also will output fail download although it can download successfully?

You may try to download this 5 image to see the result?

http://forensics.inf.tu-dresden.de/ddimgdb/images/gallery/Nikon_D200_0_15434.NEF
http://forensics.inf.tu-dresden.de/ddimgdb/images/gallery/Nikon_D200_0_15436.NEF
http://forensics.inf.tu-dresden.de/ddimgdb/images/gallery/Nikon_D200_0_15438.NEF
http://forensics.inf.tu-dresden.de/ddimgdb/images/gallery/Nikon_D200_0_15440.NEF
http://forensics.inf.tu-dresden.de/ddimgdb/images/gallery/Nikon_D200_0_15442.NEF

[Walter Roberson]

I have tightened up the code a bit, improved the handling of empty lines (which can happen at end of file for example.) Also I added in a check to skip existing files, as an optimization, so if you want a file re-downloaded then delete the saved version. I still add the skipped file to the list of URLs and matching destination files, urls and img_files

[matlabgeek]

Wonderful code. I learn a lot from your code, like fullfile(), fgetl(), and so on, these functions I first use. Thank you. You are truly number one in Matlab Answer this domain.

[matlabgeek]

Sir, do you have any personal website or social network account for us to follow. I think I can learn a lot from your experienced coding ability. It looks like you write matlab as you do the computing for 1 + 1 = 2, very excellent matlab coding ability

[Walter Roberson]

On social media I do not talk about programming much. I talk about programming so much here that social media is my escape from that, where I post about politics or post random science stories or (more often) post weird news like escaping Llamas, or Florida Man. It is not a "professional" presence and it won't help you learn to program. But if I haven't discouraged you sufficiently, you can find me on Google Plus under the same name I use here. My icon is a Japanese stone statue of a type of Japanese daemon.

[matlabgeek]

Haha, the more weired news, the more I am interested. I already followed your Google +. Thanks