如何统计pandas数据框中选定列的唯一值组合，包括值为0的频率？

selected_column = df['column_name']

value_counts = selected_column.value_counts()

value_counts_with_zero = value_counts.append(pd.Series([len(df) - len(selected_column)], index=[0]))

import pandas as pd

# 创建示例数据框
data = {'column_name': [1, 2, 3, 0, 1, 2, 0, 0]}
df = pd.DataFrame(data)

# 选择要统计的列
selected_column = df['column_name']

# 统计唯一值组合
value_counts = selected_column.value_counts()

# 添加值为0的频率
value_counts_with_zero = value_counts.append(pd.Series([len(df) - len(selected_column)], index=[0]))

print(value_counts_with_zero)

0    3
1    2
2    2
3    1
dtype: int64