How to merge multiple lists of tuples in python

Question

I have multiple lists of tuples containing a name and a count and I want to merge them by their name with the sum of their respective count. For example, I have :

l1 = [('House', 3),('Backyard', 2),('Frontyard', 4)]
l2 = [('House', 10),('street', 7),('Frontyard', 4)]
l3 = [('Backyard', 10),('street', 7),('Frontyard', 4)]

And I would like to get:

result : [('house', 13),('Backyard', 12), ('street', 14), ('Frontyard', 12)]

Essentially the same: [Python: Elegantly merge dictionaries with sum() of values](http://stackoverflow.com/questions/11290092/python-elegantly-merge-dictionaries-with-sum-of-values). They need the dictionary, you need the result of `dictionary.items()`. — vaultah, Jul 13 '15 at 20:34

score 0 · Answer 1 · answered Jul 13 '15 at 20:37

0

Just use a single dictionary for totalizing...

result = {}
for L in l1, l2, l3:
    for key, value in L:
        result[key] = result.get(key, 0) + value

# convert to a list
result = list(result.items())

answered Jul 13 '15 at 20:37

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How to merge multiple lists of tuples in python

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