For a dictionary of the type
{'key1': ['v1','v2','v3', ...], 'key2': ['v2','v4', ...], ... }How do I
- Find any key associated with a value v
- Print that k:[value set] pair to a new dictionary
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由 
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翻译强力驱动问题:
回答1:
# answer to 1st question keys_with_value = [k for k, v in old_dict.iteritems() if "whatever_value" in v] # answer to 2nd question new_dict = {} for k in keys_with_value: new_dict[k] = old_dict[k]Example:
>>> old_dict = {'key1':['v1','v2','v3'], 'key2':['v2','v4']} >>> keys_with_value = [k for k, v in old_dict.iteritems() if "v2" in v] >>> new_dict = {} >>> for k in keys_with_value: new_dict[k] = old_dict[k] >>> new_dict {'key2': ['v2', 'v4'], 'key1': ['v1', 'v2', 'v3']} >>> new_dict = {} >>> keys_with_other_value = [k for k, v in old_dict.iteritems() if "v1" in v] >>> for k in keys_with_other_value: new_dict[k] = old_dict[k] >>> new_dict {'key1': ['v1', 'v2', 'v3']}回答2:
Actually it's faster and simpler to answer the second question (put any matching pairs found into a new_dictionary) first, then just extract the list of keys from it to answer the first question.
old_dict = {'key1': ['v1','v2','v3','v56','v99'], 'key2': ['v2','v4','v42','v17'], 'key3': ['v0','v3','v4','v17','v49'], 'key4': ['v23','v14','v42'], } v = 'v42' new_dict = dict(pair for pair in old_dict.iteritems() if v in pair[1]) print 'new_dict:', new_dict # new_dict: {'key2': ['v2', 'v4', 'v42', 'v17'], 'key4': ['v23', 'v14', 'v42']} keys_with_value = new_dict.keys() print 'keys_with_value:', keys_with_value # keys_with_value: ['key2', 'key4']回答3:
In python 3 it's even nicer:
>>> old_dict = {'key1':['v1','v2','v3'], 'key2':['v2','v4']} >>> keys_with_value = [k for k, v in old_dict.items() if "v2" in v] >>> new_dict = {k: v for k, v in old_dict.items() if "v2" in v}Same result as Daniel DiPaolo has. Note the .items() instead of .iteritems().