paired_characters.py

gistfile1.txt

#!/usr/bin/env python
"""
A script to find words in which every pair of adjacent characters
appears at least twice, by going through the Unix word list.

This was written for a Stack Exchange question:
http://puzzling.stackexchange.com/q/17471/4692
"""


def pairs(word):
    """Yield successive pairs of consecutive letters from the word."""
    for i in xrange(len(word) - 1):
        yield word[i:i+2]


with open('/usr/share/dict/words') as f:
    for idx, line in enumerate(f):
        word = line.strip().lower()
        
        if len(word) <= 2:
            continue
        
        for pair in pairs(word):
            if word.count(pair) < 2:
                break
        else:
            print line.strip()

Perhaps this will be simpler?:

def test(w):
    if len(w)>1:
        l = []
        for i in range(1,len(w)):
            p=w[i-1]+w[i]
            l+=[p]
        l2 = set(l)
        return len(l)/len(l2)==2
    return False

Used as: test(word)? I wrote this for the same question.