Create (sane/safe) filename from any (unsafe) string

Question

I want to create a sane/safe filename (i.e. somewhat readable, no \"strange\" characters, etc.) from some random Unicode string (mich might contain just anything).

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Answer 1

My requirements were conservative ( the generated filenames needed to be valid on multiple operating systems, including some ancient mobile OSs ). I ended up with:

    "".join([c for c in text if re.match(r'\w', c)])

That white lists the alphanumeric characters ( a-z, A-Z, 0-9 ) and the underscore. The regular expression can be compiled and cached for efficiency, if there are a lot of strings to be matched. For my case, it wouldn't have made any significant difference.