Check whether column value is in another column which values is a list

Question

I have two columns in a dataframe. The first one contains a string in each row. The second contains a set of strings for each row. How can i check, for each row, whether the value from the first column is in the set of the second using pandas functions and that its efficient?

pd.DataFrame([np.random.randint(5, size=12), np.random.randint(5, size=(12,5))]).T

How to check if the value from column 0 in the list of column 1

Answer 1

with a list comprehension and zip (IMO this will be faster than apply):

df=df.assign(Check=[a in b for a,b in zip(df[0],df[1])])

---

    0                1  Check
0   4  [4, 4, 2, 3, 0]   True
1   4  [1, 0, 2, 1, 4]   True
2   0  [2, 1, 1, 2, 2]  False
3   0  [0, 3, 3, 2, 3]   True
4   4  [3, 0, 0, 3, 1]  False
5   1  [0, 2, 0, 3, 4]  False
6   0  [4, 3, 4, 1, 1]  False
7   1  [2, 0, 0, 3, 1]   True
8   2  [3, 3, 3, 2, 4]   True
9   2  [3, 0, 0, 4, 1]  False
10  0  [3, 3, 3, 4, 3]  False
11  1  [0, 3, 3, 2, 1]   True

Performance on the test data: