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pythonlistdictionarylookup
William Merritt
William Merritt

Reputation: 439

Lookup if Dictionary key contains items in Python

If I have the following dictionary and list, is there a way that I can looking is the items in the list are contained within the keys of the dictionary?

I tried inverting the dictionary and looking up the values, but keys cant have the same values so it messes up the schema. 

('dict', {'2D 4D': 0, '1B 2C': 0})
('list', ['2B', '2D', '3D', '4D', '4A'])

so when you ask something similar to 

if key in dict:  //if '2D' is in dict
dict[key]+=1     //{'2D 4D': 1}

Upvotes: 1

Views: 160

Answers (2)

Shehan Ishanka
Shehan Ishanka

Reputation: 593

If keys of the dict are assumed to be in the way of having a space in the middle, you can use this also.

a = {'2D 4D': 0, '1B 2C': 0}
b = ['2B', '2D', '3D', '4D', '4A']
for i in a.keys():
    a[i]=len(set(i.split()).intersection(b))

OUTPUT:

 {'2D 4D': 2, '1B 2C': 0}

Upvotes: 0

Rocky Li
Rocky Li

Reputation: 5958

You can compare each dict key entry to all in your list. For clean code purposes, don't use dict/list as var names:

mdict = {'2D 4D': 0, '1B 2C': 0}
mlist = ['2B', '2D', '3D', '4D', '4A']
for k in mdict.keys():
    for e in mlist:
        if e in k:
            mdict[k] += 1
# mdict:
{'1B 2C': 0, '2D 4D': 2}

If you have a huge list of words or dictionary entries, this will be slow. I suggest implementing a trie of your list entries and iterate with that, which will reduce the complexity from O(M*N) to O(N+M).

Upvotes: 2

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