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I have md5 hash string, e.g:

_hash = '743a0e0c5c657d3295d347a1f0a66109'

I want to write function that splits passed string to path in nginx cache format:

print hash2path(_hash, [1, 2, 3])
# outputs '7/43/a0e/743a0e0c5c657d3295d347a1f0a66109'

This is my variant:

def hash2path(_hash, levels):
    hash_copy = _hash
    parts = []
    for level in levels:
        parts.append(_hash[:level])
        _hash = _hash[level:]
    parts.append(hash_copy)  
    return '/'.join(parts)

Can you suggest better variant?

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1 Answer

up vote 2 down vote

Why you can't just hardcode cache path calculation?

>>> _hash = '743a0e0c5c657d3295d347a1f0a66109'
>>> def hash2path(_hash):
...     return "%s/%s/%s/%s" % (_hash[0], _hash[1:3], _hash[3:6], _hash)
... 
>>> hash2path(_hash)
'7/43/a0e/743a0e0c5c657d3295d347a1f0a66109'

UPDATE: If you really need to pass level array there is a little bit faster version:

def hash2path(_hash, levels):
    prev = 0
    parts = []
    for level in levels:
        parts.append(_hash[prev:prev + level])
        prev += level
    parts.append(_hash)
    return "/".join(parts)
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The point is to pass level array to function – San4ez Dec 30 '11 at 7:49
Thank you, Dmitry. But it doesn't work correct. – San4ez Dec 30 '11 at 18:30
Works if prev += level is in 6th line – San4ez Dec 30 '11 at 18:38
Ah, you're right. I didn't test it thoroughly. – hdima Dec 30 '11 at 22:21

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