How to remove elements from a Python dictionary based on elements in a list?

Question

I have a list of tuples:

lst=[(6, 'C'), (6, 'H'), (2, 'C'), (2, 'H')]

And a dictionary:

dct={'6C': (6, 'C'), '6H': (6, 'H'), '9D': (9, 'D'), '10D': (10, 'D'), '11S': (11, 'S'), '2C': (2, 'C'), '2H': (2, 'H')}

How can I remove the elements from the dictionary that are in the list? In this example my desired output would be:

dct2={'9D': (9, 'D'), '10D': (10, 'D'), '11S': (11, 'S')}

Answer 1

我会使用字典理解来映射键与列表中找不到的值：

new_dict = {k: v for k, v in old_dict.items() if v not in the_list} # filter from the list

Answer 2

If you're on Python 2 try this:

for key, value in dct.items():
    if value in lst:
        del dct[key]

EDIT:

A solution that works in both Python 2 and 3:

dict((key, value) for key, value in dct.items() if value not in lst)

Answer 3

Using the valfilter function from toolz :

from toolz import valfilter
valfilter(lst.__contains__, dct)

Answer 4

I would make the lst set before filtering out elements, since it is data structure which let's you test if element is present more efficiently.

purge_set = set(lst)
dict(filter(lambda (k, v): v not in purge_set, dct.iteritems()))