如何检查pandas.DataFrame中哪一列是确定值？

import pandas as pd

# 创建一个示例DataFrame
data = {
    'A': [1, 1, 1],
    'B': [2, 3, 4],
    'C': ['x', 'x', 'x']
}
df = pd.DataFrame(data)

# 检查哪一列是确定值
def find_deterministic_columns(df):
    deterministic_columns = []
    for column in df.columns:
        if df[column].nunique() == 1:
            deterministic_columns.append(column)
    return deterministic_columns

# 调用函数并打印结果
deterministic_columns = find_deterministic_columns(df)
print("确定值列:", deterministic_columns)

# 处理NaN值，将它们视为单独的值
df = df.fillna('NaN')

# 再次调用函数检查确定值列
deterministic_columns = find_deterministic_columns(df)
print("处理NaN后的确定值列:", deterministic_columns)