使用python将计算结果四舍五入到小数点后两位

Question

对编码和Python非常陌生。我试图将计算结果限制在小数点后两位，或者我想要的任意位数。通过谷歌发现了使用小数，但我无法让我的代码工作。

我从开始

amount_per_day = amount_of_money/currency_amount
print("If you are going to spend " + str(amount_of_money) + " " + str(destination_currency) + " that means that you can spend up to " + str(amount_per_day) + " " + Home_currency + " per day to remain in budget.")

我尝试了

from decimal import Decimal
amount_per_day = Decimal(amount_of_money/currency_amount)
amount_per_day_to_two_decimal_places = round(amount_per_day,2)
print("If you are going to spend " + str(amount_of_money) + " " + str(destination_currency) + " that means that you can spend up to " + str(amount_per_day) + " " + Home_currency + " per day to remain in budget.")

结果

如果你打算花费2000.0欧元，这意味着你每天最多可以花费1818.181818181818016455508768558502197265625英镑来保持预算。

代码有效，但我不需要39位小数的答案。

Answer 1

只需使用round(x, 2)，其中x是您的变量

Answer 2

一旦用39位小数计算出amount_per_day，就可以使用内置函数"圆形"；

圆形的工作方式如下：round(float_num, num_of_decimals)
所以在您的情况下，您执行amount_per_day = round(amount_per_day, 2)

我还建议你用这样的f-string替换你在打印声明中添加的所有讨厌的字符串：

print(f"If you are going to spend {str(amount_of_money)}
{str(destination_currency)} that means that you can
spend up to {str(amount_per_day)} {Home_currency} per
day to remain in budget.")

它看起来更干净，实际上也更快

Answer 3

Python有一个内置的函数round。文档中对此进行了深入介绍。

因此，在您的情况下，您要查找的结果是round(amount_per_day, 2)。请注意，这将把输出更改为小数点后2位(因此将有效地截断第二个小数点后的剩余小数点(，并且在偶数中四舍五入到最近的偶数值。

Answer 4

要取整，可以使用以下方法：

value = 1818.181818181818016455508768558502197265625    
print(round(value, 2))

您可以使用以下内容设置文本格式。

print('you can spend %.2f GBP per day' % value)