String search in lists

[Netcode]

Am new to python and i need help dealing so i would go ahead and post the question and my little solution so far.

Question: a Procedure which takes four parameters as follows;
Dictionary File- the file name of a text file containing four letter words
Start Word- a four letter word (that you can assume is found in the Dictionary File file)
End Word- a four letter word (that you can assume is found in the Dictionary File file)
Result File- the file name of a text file that will contain the result
The result is the shortest list of four letter words, starting with StartWord, and ending with EndWord, with a number of intermediate words that are to be found in the DictionaryFilefile where each word differs from the previous word by precisely one letter.

So far, i've been able to return true or false if the searched strings exist. I used a list because i didnt wanna use a file so i loaded sample words into a list. See my code below but i wanna achieve the above.

# create list of words
dicfile = ["ante", "ants", "calf", "call", "calm", "clam", "diet", "dire", "earl", "edit",
        "emit", "erst", "fail", "fate", "feat", "feta", "ires", "irks", "item", "lair",
        "lame", "late", "leap", "les", "lets", "liar", "lips", "lira","list", "lite", 
        "male", "mall", "mate", "matt", "meal", "meat", "mint", "mite", "mitt", "naps",
        "neat", "nips", "nite", "nits", "opts", "pale", "pans", "past", "pate", "pats",
        "peal", "peat", "pest", "pets", "pier", "pins", "pits", "plea", "post", "pots", 
        "rail", "rant", "rate", "real", "rest", "rial", "ride", "ripe", "rise", "risk",
        "rite", "rite", "shin", "silt", "sire", "slip", "slit", "snap", "snip", "snit", 
        "span", "spat", "spin", "spit", "spot", "step", "stop", "tale", "tall", "tame", 
        "tans", "tape", "taps", "tare", "tarn", "teal", "team", "tear", "tide", "tied",
        "tier", "tier", "tile", "time", "tine", "tins", "tint", "tips", "tire", "tire", 
        "tops", "lisp"] 

print len(dicfile)

def is_string_in_list(startword, endword, dicfile):
    for str in startword, endword:
        if str not in dicfile:
            return False
        return True

#test the function
print (is_string_in_list("stone", "son", dicfile))

[vegaseat]

I thought that startword and endword have to be four letter words?

[Gribouillis]

The 4 letters words are nodes in a graph where adjacent nodes differ by one letter from the current node. Starting from the startword, you can do a depth first walk of the graph until you reach the endword. I posted a clue for depth first traversal here (replace urls with 4 letter words).

[Netcode]

I thought that startword and endword have to be four letter words?

yes, they are both four letter words and are words assumed to be in the list. If you take a good look at the list, all words there are four letter words.

[Gribouillis]

Here is the graph, generated with this code snippet and a few more lines:

from fastgraph import graph

dicfile = ["ante", "ants", "calf", "call", "calm", "clam", "diet", "dire", "earl", "edit",
        "emit", "erst", "fail", "fate", "feat", "feta", "ires", "irks", "item", "lair",
        "lame", "late", "leap", "les", "lets", "liar", "lips", "lira","list", "lite", 
        "male", "mall", "mate", "matt", "meal", "meat", "mint", "mite", "mitt", "naps",
        "neat", "nips", "nite", "nits", "opts", "pale", "pans", "past", "pate", "pats",
        "peal", "peat", "pest", "pets", "pier", "pins", "pits", "plea", "post", "pots", 
        "rail", "rant", "rate", "real", "rest", "rial", "ride", "ripe", "rise", "risk",
        "rite", "rite", "shin", "silt", "sire", "slip", "slit", "snap", "snip", "snit", 
        "span", "spat", "spin", "spit", "spot", "step", "stop", "tale", "tall", "tame", 
        "tans", "tape", "taps", "tare", "tarn", "teal", "team", "tear", "tide", "tied",
        "tier", "tier", "tile", "time", "tine", "tins", "tint", "tips", "tire", "tire", 
        "tops", "lisp"]

def dist(word, other):
    return sum([1 if (x == y) else 0 for (x, y) in zip(word, other)])

def all_items():
    for i, word in enumerate(dicfile):
        for other in dicfile[i+1:]:
            if dist(word, other) == 3:
                yield (word, other)

if __name__ == '__main__':
    def label(x):
        return x

    g = graph(all_items(), label)
    g.draw('dicfile.png', prog='fdp') # prog can be neato|dot|twopi|circo|fdp|nop

[Netcode]

Gribouillis, thanks for your reply. However, if you read my very first statement just before the question at hand, you will know its likely you have added to my worries.

[Gribouillis]

Yes, you are new to python, but not to programming. Here is a simpler snippet to create an adjacency dictionary

dicfile = ...

def dist(word, other):
    return sum(1 if (x == y) else 0 for (x, y) in zip(word, other))

def all_items():
    for i, word in enumerate(dicfile):
        for other in dicfile[i+1:]:
            if dist(word, other) == 3:
                yield (word, other)
                yield (other, word)

if __name__ == '__main__':

    from collections import defaultdict
    from pprint import pprint

    D = defaultdict(set)
    for k, v in all_items():
        D[k].add(v)
    D = dict(D)
    pprint(D)

""" my output:
{'ante': set(['ants']),
 'ants': set(['ante']),
 'calf': set(['call', 'calm']),
 'call': set(['calf', 'calm', 'mall', 'tall']),
 'calm': set(['calf', 'call']),
 'dire': set(['sire', 'tire']),
 'edit': set(['emit']),
 'emit': set(['edit']),
 'fail': set(['rail']),
 'fate': set(['late', 'mate', 'pate', 'rate']),
 'feat': set(['meat', 'neat', 'peat']),
 ...
 """

[Netcode]

Thanks alot. Got it!