[Tutor] comparing seqs by successive intervals

[Karl Pflästerer]

On 19 Jan 2004, Daniel Ehrenberg <- littledanehren at yahoo.com wrote:

> In that algorithm, where does it check to make sure
> that one of the arrays isn't longer than the other?

Nowhere.  It wasn't specified.

> They have to be the same length or else the real
> application of seeing if they are transpositions of
> eachother will not work.

He didn't wrote that the sequences had to be of the same length.  But if
that's needed it's trivial:

def same_intervp(seq1, seq2):
    i = 0
    res = []
    if len(seq1) == len(seq2):
       [Code]
    else:
        return False

IMO that's more efficient than building two auxiliary lists and
comparing those lists.

If you compute the length anyway the code could be written a bit
different (and simpler):

def same_intervp(seq1, seq2):
    res = []
    L = len(seq1)
    if L == len(seq2):
        for i in xrange(L - 1):
            d1 = seq1[i+1] - seq1[i]
            d2 = seq2[i+1] - seq2[i]
            if d1 == d2: res.append(d1%12)
            else: return False
        return res
    else: return False



   Karl
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