如何截取二维双精度数组中某些双精度数的小数位？

import numpy as np

def truncate_decimal(arr, decimal_places):
    result = []
    for row in arr:
        truncated_row = []
        for num in row:
            num_str = str(num)
            decimal_index = num_str.find('.')
            if decimal_index != -1:
                truncated_num_str = num_str[:decimal_index + decimal_places + 1]
                truncated_num = float(truncated_num_str)
                truncated_row.append(truncated_num)
            else:
                truncated_row.append(num)
        result.append(truncated_row)
    return np.array(result)

# 示例用法
arr = np.array([[1.23456789, 2.3456789], [3.456789, 4.56789]])
decimal_places = 3
truncated_arr = truncate_decimal(arr, decimal_places)
print(truncated_arr)