Slicing a dictionary by keys that start with a certain string

Question

This is pretty simple but I'd love a pretty, pythonic way of doing it. Basically, given a dictionary, return the subdictionary that contains only those keys that start with a certain string.

» d = {'Apple': 1, 'Banana': 9, 'Carrot': 6, 'Baboon': 3, 'Duck': 8, 'Baby': 2} » print slice(d, 'Ba') {'Banana': 9, 'Baby': 2, 'Baboon': 3} 

This is fairly simple to do with a function:

def slice(sourcedict, string):     newdict = {}     for key in sourcedict.keys():         if key.startswith(string):             newdict[key] = sourcedict[key]     return newdict 

But surely there is a nicer, cleverer, more readable solution? Could a generator help here? (I never have enough opportunities to use those).

Answer 1

How about this:

in python 2.x :

def slicedict(d, s):     return {k:v for k,v in d.iteritems() if k.startswith(s)} 

In python 3.x :

def slicedict(d, s):     return {k:v for k,v in d.items() if k.startswith(s)} 

Answer 2

In functional style:

dict(filter(lambda item: item[0].startswith(string),sourcedict.iteritems()))