Python - Find a tuple in list of lists

Question

I have list of tuples ( mytuples ) and a list of lists ( mylist ).

I want to find how many times each tuple in mytuples occurs in every list.

Say tuple (2,3) occurs in [1,2,3,4] , [2,3,4,5] and [2,3] . Therefore count of (2,3) is 3 .

Tuple and list size can be different.

mytuples = [(2,3), (3,6), (1,2)]
mylist = [[1,2,3,4],[2,3,4,5],[2,3],[4,5,6]]

count={}    
for m in mytuples :
    counter = 0        
    for i in mylist :
        if set(m).issubset(i):
            counter = counter + 1
    count[m]=counter

My output would be {(2,3):3, (3,6): 0, (1,2):1}

This approach works fine but when my list size is huge say 1000 of records, it is more time consuming. Can this be done faster? any suggestions?

Answer 1

Using dict comprehension we could reduce everything to one single-line.

And assuming the tuples are always pairs:

count = {(x,y):sum((x in i and y in i) for i in mylist) for x,y in mytuples}
# {(1, 2): 1, (2, 3): 3, (3, 6): 0}

Or you could sum using all() if tuple size is unkown:

count = {t:sum(all(x in i for x in t) for i in mylist) for t in mytuples}
# {(1, 2): 1, (2, 3): 3, (3, 6): 0}

---

If this isn't clear:

We go through multiple of these:

[all(x in i for x in (2,3)) for i in mylist]
# [True, True, True, False] 
# sum([True, True, True, False]) = 3
# And we assign them back to the tuple

Answer 2

Your current algorithm can be made somewhat faster with a small adjustment:

# Your input data.
tuples = [(2,3), (3,6), (1,2)]
lists = [[1,2,3,4],[2,3,4,5],[2,3],[4,5,6]]

# Convert to sets just once, rather than repeatedly
# within the nested for-loops.
subsets = {t : set(t) for t in tuples}
mainsets = [set(xs) for xs in lists]

# Same as your algorithm, but written differently.
tallies = {
    tup : sum(s.issubset(m) for m in mainsets)
    for tup, s in subsets.items()
}

print(tallies)