import pandas as pd
data = {'date': ['2021-01-01', '2021-01-05', '2021-02-10', '2021-03-15', '2021-03-20'], 'value': [10, 15, 20, 25, 30]} df = pd.DataFrame(data)
df['date'] = pd.to_datetime(df['date'])
df_count = df.groupby([df['date'].dt.year, df['date'].dt.month]).count()
print(df_count)