# import necessary libraries
import pandas as pd
import re

# create a sample pandas series
emails = pd.Series(['[email protected]', 'invalid email', \
                    'fake_email.com', '[email protected]'])

# define regex pattern
pattern = r'[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}'

# define lambda function
is_valid = lambda x: re.match(pattern, x) is not None

# apply lambda function using apply()
valid_emails = emails[emails.apply(is_valid)]

# print results
print(valid_emails)