Finding the intersection between two series in Pandas

python pandas series intersection
user7289 picture user7289 · Aug 6, 2013 · Viewed 91.8k times · Source

I have two series s1 and s2 in pandas and want to compute the intersection i.e. where all of the values of the series are common.

How would I use the concat function to do this? I have been trying to work it out but have been unable to (I don't want to compute the intersection on the indices of s1 and s2, but on the values).

Answer

Joop picture Joop · Aug 6, 2013

Place both series in Python's set container then use the set intersection method:

s1.intersection(s2)

and then transform back to list if needed.

Just noticed pandas in the tag. Can translate back to that:

pd.Series(list(set(s1).intersection(set(s2))))

From comments I have changed this to a more Pythonic expression, which is shorter and easier to read:

Series(list(set(s1) & set(s2)))

should do the trick, except if the index data is also important to you.

Have added the list(...) to translate the set before going to pd.Series as pandas does not accept a set as direct input for a Series.

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