Match list values to dict and return key/value pairs in new dict

Question

I have a list that represents the values of a dictionary. I am trying to parse the dictionary looking for values that are also in my list and creating a new dictionary from this that contains only the matched values:

a = [1, 2, 3]
b = {"aye":1, "bee":2, "cee":3, "dee":4, "eee":5}

new_dict = dict((k, v) for k, v in b.iteritems() if k in a)
print new_dict

My desired output should look like this:

new_dict = {"aye":1, "bee":2, "cee":3}

However, all I am getting back is:

{}

Can anyone tell me where I am going wrong?

Answer 1

k represents the keys and v the values

>>> a = [1, 2, 3]
>>> b = {"aye":1, "bee":2, "cee":3, "dee":4, "eee":5}
>>> new_dict = dict((k, v) for k, v in b.iteritems() if v in a)
>>> print new_dict
{'aye': 1, 'cee': 3, 'bee': 2}

So therefore to achieve what you want, you have to do if v in a instead.