I have a folder with hundreds of .xlsx files which are daily data from years ago.

The file name pattern is 'ABC DEF 20150501.xlsx'

How can I pick files from the last day of each months for all these years.

Sadly I have no clue how to do it.

```
import pandas as pd
import re

files = [f for f in os.listdir(path) if re.match(r'ABC DEF [0-9]+.xlsx', f)]
df = pd.DataFrame(files)
df.columns = ['file_name']
df['port_date'] = df['file_name'].apply(lambda x : x.split(' ')[3].split('.')[0])

```

I got only the date in one column, and run out of idea!

Any help will be appreciated.