how to check if 3 characters are in consecutive alpha order

alphabetical, python, sequence

Solution

Easy:

>>> letters = "Cde"
>>> from string import ascii_lowercase
>>> letters.lower() in ascii_lowercase
True
>>> letters = "Abg"
>>> letters.lower() in ascii_lowercase
False

Alternatively, one could use `string.find()`.

>>> letters = "lmn"
>>> ascii_lowercase.find(letters) != -1
True

I guess a function using this would look like:

def checkSequence(*letters):
    return ''.join(letters).lower() in ascii_lowercase

Problem

Just curious, what's the most pythonic/efficient way to determine if sequence of 3 characters are in consecutive alpha order? Below a quick&dirty way that seems to work, other, nicer implementations? I suppose one alternative approach might be to sort a copy the sequence and compare it with the original. Nope, that wouldn't account for gaps in the sequence. (This is not homework - listeners to NPR Sunday Morning progam will know) ``` def checkSequence(n1, n2, n3): """ check for consecutive sequence of 3 """ s = ord('a') e = ord('z') # print n1, n2, n3 for i in range(s, e+1): if ((n1+1) == n2) and ((n2+1) == n3): return True return False def compareSlice(letters): """ grab 3 letters and sent for comparison """ letters = letters.lower() if checkSequence(ord(letters[0]), ord(letters[1]), ord(letters[2])): print '==> seq: %s' % letters return True return False ```

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