pandas isin

The `isin()` function in the pandas library is used to filter a DataFrame or Series based on whether its elements are contained in a specified set or list. It returns a boolean mask indicating whether each element is in the specified set or list.

Here's an example of how you can use `isin()`:

import pandas as pd

# create a DataFrame
data = {'col1': [1, 2, 3, 4, 5],
        'col2': ['a', 'b', 'c', 'd', 'e']}
df = pd.DataFrame(data)

# filter the DataFrame based on values in col1
filtered_df = df[df['col1'].isin([2, 4])]
print(filtered_df)

Output:

   col1 col2
1     2    b
3     4    d

In this example, `isin([2, 4])` filters the rows in the DataFrame where the values in `col1` are either 2 or 4. The resulting DataFrame (`filtered_df`) contains only the rows with those values.