How can I get multiple shared items between two dictionaries in Python?

Question

length_word = {'pen':3, 'bird':4, 'computer':8, 'mail':4} 
count_word = {'pen':10, 'bird':50, 'computer':3, 'but':45, 'blackboard': 12, 'mail':12}

intersection = length_word.items() - count_word.items() 
common_words = {intersection}

Err: TypeError: unhashable type: 'set'

I wish to get this dictionary:

outcome = {'pen':10, 'bird':50, 'computer':3, 'mail':12}

Thanks.

A set as an unhashable type can not be part of an other set nor a key in a dictionary. — Klaus D., Mar 10 '21 at 17:33
See this post, it answers your question: https://stackoverflow.com/questions/18554012/intersecting-two-dictionaries-in-python — sander, Mar 10 '21 at 17:37

score 0 · Answer 1 · answered Mar 10 '21 at 17:37

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intersection = count_word.keys() & length_word.keys()    

outcome = dict((k, count_word[k]) for k in intersection)

answered Mar 10 '21 at 17:37

moe9195

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score 0 · Answer 2 · answered Mar 10 '21 at 17:39

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try getting the intersection (common keys). one you have the common keys access those keys from the count_words.

res = {x: count_word.get(x, 0) for x in set(count_word).intersection(length_word)}

res:

{'bird': 50, 'pen': 10, 'computer': 3, 'mail': 12}

answered Mar 10 '21 at 17:39

Pygirl

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Why use `get` with a default rather than `count_word[x]`? – superb rain Mar 10 '21 at 17:51
@superbrain: Yes actually If you are going for union thing then use `get`. For this case it's not required to use get so yeah one can use directly also. – Pygirl Mar 10 '21 at 17:55

Rima · Answer 3 · 2021-03-10T18:14:38.490

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Using for loop check if the key is present in both the dictionary. If so then add that key, value pair to new dictionary.

length_word = {'pen':3, 'bird':4, 'computer':8, 'mail':4}
count_word = {'pen':10, 'bird':50, 'computer':3, 'but':45, 'blackboard': 12, 'mail':12}
my_dict = {}

for k, v in count_word.items():
    if k in length_word.keys():
        my_dict[k] = v

print(my_dict)

edited Mar 10 '21 at 18:14

answered Mar 10 '21 at 17:44

Rima

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Why not simply `if k in length_word:`? – superb rain Mar 10 '21 at 17:56
Yes we can do that. Can you please explain what is the difference between two? – Rima Mar 10 '21 at 18:06
Hmm, I'd say the difference is that one way does useless extra work and the other doesn't :-). I can't tell why you did that extra work, only you know. – superb rain Mar 10 '21 at 18:08
I mean, `.keys()` every time creates an keys view object for no benefit, and the whole second half of your condition checks whether the key is in the dict that you just got it from. – superb rain Mar 10 '21 at 18:12
Yes you are right. I corrected my code. Thank you. – Rima Mar 10 '21 at 18:16

score 0 · Accepted Answer · answered Mar 10 '21 at 17:45

You should use .keys() instead of .items(). Here is a solution:

length_word = {'pen':3, 'bird':4, 'computer':8, 'mail':4}
count_word = {'pen':10, 'bird':50, 'computer':3, 'but':45, 'blackboard': 12, 'mail':12}
intersection = count_word.keys() & length_word.keys()    

common_words = {i : count_word[i] for i in intersection}

#Output: 
{'computer': 3, 'pen': 10, 'mail': 12, 'bird': 50}

score 0 · Answer 5 · answered Mar 10 '21 at 18:01

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Just another dict comp:

outcome = {k: v for k, v in count_word.items() if k in length_word}

answered Mar 10 '21 at 18:01

superb rain

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How can I get multiple shared items between two dictionaries in Python?

5 Answers5