Reply to thread

Message: [QUOTE="Steven D'Aprano, post: 5058484"] According to your example code, you don't have to split the input because you already have two lists, one filled with numbers and one filled with strings. But I think that what you actually have is a single list of strings, and you are supposed to sort the strings such that they come in numeric order first, then alphanumerical. E.g.: ['9', '1000', 'abc2', '55', '1', 'abc', '55a', '1a'] => ['1', '1a', '9', '55', '55a', '1000', 'abc', 'abc2'] At least that is what I would expect as the useful thing to do when sorting. The trick is to take each string and split it into a leading number and a trailing alphanumeric string. Either part may be "empty". Here's a pure Python solution: from sys import maxsize # use maxint in Python 2 def split(s): for i, c in enumerate(s): if not c.isdigit(): break else: # aligned with the FOR, not the IF return (int(s), '') return (int(s[:i] or maxsize), s[i:]) Now sort using this as a key function: py> L = ['9', '1000', 'abc2', '55', '1', 'abc', '55a', '1a'] py> sorted(L, key=split) ['1', '1a', '9', '55', '55a', '1000', 'abc', 'abc2'] The above solution is not quite general: * it doesn't handle negative numbers or numbers with a decimal point; * it doesn't handle the empty string in any meaningful way; * in practice, you may or may not want to ignore leading whitespace, or trailing whitespace after the number part; * there's a subtle bug if a string contains a very large numeric prefix, finding and fixing that is left as an exercise. [/QUOTE]

Verification