python保留小数点位数的多种方式(附demo)

value = 3.141592653589793
formatted_value = f"{value:.2f}"
print(formatted_value)  # 输出: 3.14

value = 3.141592653589793
formatted_value = "{:.2f}".format(value)
print(formatted_value)  # 输出: 3.14

value = 3.141592653589793
formatted_value = "%.2f" % value
print(formatted_value)  # 输出: 3.14

value = 3.141592653589793
rounded_value = round(value, 2)
print(rounded_value)  # 输出: 3.14

from decimal import Decimal, ROUND_HALF_UP

value = Decimal('3.141592653589793')
rounded_value = value.quantize(Decimal('0.01'), rounding=ROUND_HALF_UP)
print(rounded_value)  # 输出: 3.14

import numpy as np

value = 3.141592653589793
rounded_value = np.round(value, 2)
print(rounded_value)  # 输出: 3.14

import numpy as np
from decimal import Decimal, ROUND_HALF_UP

value = 3.141592653589793

# 使用f-strings
formatted_value_f = f"{value:.2f}"
print(f"f-strings: {formatted_value_f}")

# 使用str.format()
formatted_value_format = "{:.2f}".format(value)
print(f"str.format(): {formatted_value_format}")

# 使用百分号 (%) 格式化
formatted_value_percent = "%.2f" % value
print(f"百分号格式化: {formatted_value_percent}")

# 使用round()函数
rounded_value_round = round(value, 2)
print(f"round(): {rounded_value_round}")

# 使用Decimal模块
decimal_value = Decimal('3.141592653589793')
rounded_value_decimal = decimal_value.quantize(Decimal('0.01'), rounding=ROUND_HALF_UP)
print(f"Decimal模块: {rounded_value_decimal}")

# 使用numpy库
rounded_value_numpy = np.round(value, 2)
print(f"numpy库: {rounded_value_numpy}")