为什么我不能在Pandas上创建两个具有不同移动平均窗口的列？

import pandas as pd
import numpy as np

# 创建一个示例DataFrame
data = {'A': [1, 2, 3, 4, 5],
        'B': [6, 7, 8, 9, 10]}
df = pd.DataFrame(data)

# 定义移动平均函数
def moving_average(data, window):
    weights = np.repeat(1.0, window) / window
    ma = np.convolve(data, weights, 'valid')
    return np.concatenate((np.full(window-1, np.nan), ma))

# 创建具有不同移动平均窗口的多个列
df['A_ma_2'] = moving_average(df['A'], 2)
df['A_ma_3'] = moving_average(df['A'], 3)
df['B_ma_2'] = moving_average(df['B'], 2)
df['B_ma_4'] = moving_average(df['B'], 4)

print(df)

   A   B  A_ma_2  A_ma_3  B_ma_2  B_ma_4
0  1   6     NaN     NaN     NaN     NaN
1  2   7     1.5     NaN     6.5     NaN
2  3   8     2.5     2.0     7.5     NaN
3  4   9     3.5     3.0     8.5    7.50
4  5  10     4.5     4.0     9.5    8.25