CODEWITHSUNDEEP
python
EmJ
EmJ

Reputation: 4618

How to efficiently combine tuples in a list when similar elements in python

I have list in the format of:

mylist = [["emi", [["python", "is", "cool"], ["i", "love", "python"]]],
           ["jenne", [["cool", "fun", "home"]]],
           ["lin", [["networking", "is", "hard"], ["i", "hate", "networking"]]],
           ["jim", [["party"]]],
           ["emi", [["i", "love", "machine learning"]]],
           ["jenne", [["homework"]]]]

I want to combine the lists of similar users. In other words, my output is;

myoutput = [["emi", [["python", "is", "cool"], ["i", "love", "python"], ["i", "love", "machine learning"]]],
           ["jenne", [["cool", "fun", "home"], ["homework"]]],
           ["lin", [["networking", "is", "hard"], ["i", "hate", "networking"]]],
           ["jim", [["party"]]]]

I use the following code to do this.

myoutput = []
for i, item in enumerate(mylist):
    mytemp = []
    for sentence in item[1]:
        mytemp.append(sentence)    

    for j, newitem in enumerate(mylist):
        if i != j:
            if item[0] == newitem[0]:
                for sent in newitem[1]:
                    mytemp.append(sent)

However, my code is O(n)^2. I think there is more efficient way of handling this in python. Please let me know your thoughts to make this more efficient.

I am happy to provide more details if needed.

Upvotes: 0

Views: 53

Answers (1)

Abhishek J
Abhishek J

Reputation: 2584

We first read the entire list of lists into a dict. After that we merely convert the dict back into a list of lists.

Also note the if condition below. If the name of the user is already in the dict, we just append to the list in the dict

mylist = [["emi", [["python", "is", "cool"], ["i", "love", "python"]]],
          ["jenne", [["cool", "fun", "home"]]],
          ["lin", [["networking", "is", "hard"], ["i", "hate", "networking"]]],
          ["jim", [["party"]]],
          ["emi", [["i", "love", "machine learning"]]],
          ["jenne", [["homework"]]]]

def convert():
    d = {}
    for user in mylist:
        if user[0] in d: # Condition that user is already present.
            for arr in user[1]:
                d[user[0]].append(arr)
            continue
        d[user[0]] = user[1] # User not present. Therefore added a key in the dict
    ans = [[k,v] for k,v in d.items()] # Converting dict to list of lists
    print(ans)
    return ans



#OUTPUT
[['emi', [['python', 'is', 'cool'], ['i', 'love', 'python'], ['i', 'love', 'machine learning']]],
['jenne', [['cool', 'fun', 'home'], ['homework']]],
['lin', [['networking', 'is', 'hard'], ['i', 'hate', 'networking']]],
['jim', [['party']]]]

Upvotes: 3

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