Cranky Frankie wrote:
> In playing around with Pyton 3 dictionaries I've come up with 2 questions
>
> 1) How are duplicate keys handled? For example:
>
> Qb_Dict = {"Montana": ["Joe", "Montana", "415-123-4567",
> "[email protected]","Candlestick Park"],
> "Tarkington": ["Fran", "651-321-7657", "[email protected]",
> "Metropolitan Stadidum"],
> "Namath": ["Joe", "212-222-7777", "[email protected]", "Shea Stadium"],
> "Elway": ["John", "303-9876-333", "[email protected]", "Mile High
> Stadium"], "Elway": ["Ed", "303-9876-333", "[email protected]", "Mile
> High Stadium"],
> "Manning": ["Archie","504-888-1234", "[email protected]",
> "Louisiana Superdome"],
> "Staubach": ["Roger","214-765-8989", "[email protected]",
> "Cowboy Stadium"]}
>
> print(Qb_Dict["Elway"],"\n") # print a dictionary
> entry
>
> In the above the "wrong" Elway entry, the second one, where the first
> name is Ed, is getting printed. I just added that second Elway row to
> see how it would handle duplicates and the results are interesting, to
> say the least.
The last one always wins. Perhaps it becomes clearer if you think of
d = {1:1, 1:2}
as syntactic sugar for
d = dict()
d[1] = 1
d[1] = 2
If you want to allow for multiple values per key use a list as the value and
append to that:
>>> d = {}
>>> for k, v in [(1, 1), (2, 2), (1, 3)]:
... d.setdefault(k, []).append(v)
...
>>> d
{1: [1, 3], 2: [2]}
> 2) Is there a way to print out the actual value of the key, like
> Montana would be 0, Tarkington would be 1, etc?
No, the actual key *is* "Montana" or "Tarkington". The dictionary does not
record the insertion order.
There is a collections.OrderedDict, but I recommend that you don't try out
that until you have grokked the builtin dict. As a rule of thumb there are
less usecases for an OrderedDict than you think ;)
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