Add random filenames feature

[butchland]

Hi Joe,

This is just a feature enhancement that allows the filenames to have a random string tacked on at the end, allowing the filenames to be unique, even across directories.

This is to fix a problem with running the fastai.vision.widgets.ImageClassifierCleaner which moves the images across the folders if you change their categories.

This in turn, triggers an error because the filenames are unique within a folder, but not across the different category folders (e.g. reclassifying 003.jpg in teddys folder to a grizzly could trigger an error because there might already be a file named 003.jpg in the grizzly folder)

Adding a random string at the end of the name eg. 001_cc13976d.jpg instead 001.jpg makes sure this doesn't happen since each file will be unique even if both files start with 001.

This additional functionality is turned off by default, so everything works the same unless you explicitly pass the random_names parameter to True.

Hope you find this a useful feature to merge.

Best regards, Butch

[joedockrill]

Like it! Thanks @butchland.

[joedockrill]

@butchland FYI:

• made this the default everywhere
• renamed it uuid_names
• fixed is_file lambda in download_urls to work with uuid filenames
• pushed to pypi

thanks dude!