CODEWITHSUNDEEP
pythonset
Serafeim
Serafeim

Reputation: 15104

Going crazy with python set

Please take a look at the following snippet from ipython:

In [122]: len(netean)
Out[122]: 150

In [123]: len(nwrongpea)
Out[123]: 100

In [124]: len(set.intersection(set(nwrongpea), set(netean)))
Out[124]: 8

In [125]: len(set(nwrongpea) - set(netean))
Out[125]: 90

In [126]: len(set(netean) - set(nwrongpea))
Out[126]: 142

I am going crazy - since these two lists have the 8 elements in common (based on what intersection answers), how is it possible that [125] returns 90 ? Shouldn't that be 92 ?

Have I forgotten something from set theory ?

Thanks !

Upvotes: 2

Views: 236

Answers (1)

osa1
osa1

Reputation: 7088

It looks like one(or two) of this collections have some duplicate elements. So creating sets from them gives you sets with less number of elements..

Try len(set(natean)) + len(set(nwrongpea)) and you'll see.

Upvotes: 10

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