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pythonpython-3.xlistelementlist-comparison

Extract the different element of a List

In a list of three elements I want to find the element of a list that is different from the other two. For example I have L=[3,3,1] and I want to extract the number 1. At first I was thinking about using set() so I can compare it with a list but then I got stuck again in this code:

S=set(L)
c1=0
c2=0
for k in L:
    for i in S:
        if k==i:
            c1+=1
            v1=k
        else:
            c2+=1
            v2=k
if c1<c2:
    print (v1)
else:
    print (v2)

I tried to count how many times they appear so I can be sure with c1 and c2 will have a different value but then I realized v1 and v2 were completely wrong.

Solution

  • Find the rarest?

    >>> min(L, key=L.count)
1

    Or if they're all ints, make the duplicate pair cancel each other with xor:

    >>> L[0] ^ L[1] ^ L[2]
1