[Tutor] Counting matching elements in sequences

[Karl Pflästerer]

On  9 Dec 2003, Magnus Lycka <- magnus at thinkware.se wrote:

> import operator

> def matches4(*seqlist):
>     allSame = 0
>     for elements in zip(*seqlist):
>         allSame += reduce(operator.eq, elements)
>     return allSame 

That won't work (I first thought of the same solution) because x == y
returns True or False not x or y (with two elemenstit works, with three
it breaks).

> or if you prefer lambda to importing operator...

> def matches4(*seqlist):
>     allSame = 0
>     for elements in zip(*seqlist):
>         allSame += reduce(lambda x,y: x==y, elements)
>     return allSame 


Try the simple 

>>> reduce(operator.eq, [2,2,2])
False

So you need a function like alleq

def alleq(seq):
    return seq[0] == reduce(lambda s, t: s==t and t, seq)

>>> alleq([2,2,2])
True
>>> 


   Karl
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