Map list onto dictionary

python list functional-programming hashtable

In Python 3 you can use this dictionary comprehension syntax:

def foo(somelist):    return {x[0]:x for x in somelist}

python list functional-programming hashtable

I don't think a standard function exists that does exactly that, but it's very easy to construct one using the dict builtin and a comprehension:

def somefunction(keyFunction, values):    return dict((keyFunction(v), v) for v in values)print somefunction(lambda a: a[0], ["hello", "world"])

Output:

{'h': 'hello', 'w': 'world'}

But coming up with a good name for this function is more difficult than implementing it. I'll leave that as an exercise for the reader.

python list functional-programming hashtable

If I understand your question correctly, I believe you can accomplish this with a combination of map, zip, and the dict constructor:

def dictMap(f, xs) :    return dict(zip(map(f, xs), xs)

And a saner implementation :

def dictMap(f, xs) :    return dict((f(i), i) for i in xs)

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