向df中添加满足多个条件的单独df中的行数的列

import pandas as pd

df = pd.DataFrame({'A': [1, 2, 3, 4, 5],
                   'B': [6, 7, 8, 9, 10],
                   'C': [11, 12, 13, 14, 15]})

condition_df = df[(df['A'] > 2) & (df['B'] < 9)]

row_count = condition_df.shape[0]

df['New Column'] = row_count

import pandas as pd

df = pd.DataFrame({'A': [1, 2, 3, 4, 5],
                   'B': [6, 7, 8, 9, 10],
                   'C': [11, 12, 13, 14, 15]})

condition_df = df[(df['A'] > 2) & (df['B'] < 9)]
row_count = condition_df.shape[0]
df['New Column'] = row_count