python中round是什么意思 python四舍五入函数解析

# 基本的四舍五入
result = round(3.14159, 2)
print(result)  # 输出: 3.14

# 使用银行家舍入法
result = round(2.5)  # 结果是2
result = round(3.5)  # 结果是4
print(result)  # 输出: 4

# 浮点数精度问题
result = round(2.675, 2)
print(result)  # 可能输出: 2.67 而不是2.68

from decimal import Decimal, ROUND_HALF_UP

# 使用decimal模块进行精确四舍五入
num = Decimal('2.675')
result = num.quantize(Decimal('0.01'), rounding=ROUND_HALF_UP)
print(result)  # 输出: 2.68

import numpy as np

# 对numpy数组进行四舍五入
arr = np.array([1.234, 2.345, 3.456])
rounded_arr = np.round(arr, 2)
print(rounded_arr)  # 输出: [1.23 2.35 3.46]

import time
import numpy as np

# 比较性能
data = list(range(1000000))
start_time = time.time()
rounded_data = [round(num, 2) for num in data]
print(f"Python round: {time.time() - start_time} seconds")

data_np = np.array(data)
start_time = time.time()
rounded_data_np = np.round(data_np, 2)
print(f"NumPy round: {time.time() - start_time} seconds")

# 使用有意义的变量名和注释
def round_numbers(numbers, decimal_places):
    """
    对给定列表中的每个数字进行四舍五入。

    参数:
    numbers (list): 要进行四舍五入的数字列表
    decimal_places (int): 保留的小数位数

    返回:
    list: 四舍五入后的数字列表
    """
    return [round(num, decimal_places) for num in numbers]

# 示例使用
example_numbers = [1.234, 2.345, 3.456]
rounded_example = round_numbers(example_numbers, 2)
print(rounded_example)  # 输出: [1.23, 2.35, 3.46]