打印整数或带有n个小数的浮点数

问题描述

在Python中，当后一种情况要求我将打印输出限制为一定数量的数字时，如何打印可能是整数或实数的数字?

In Python, how can one print a number that might be an integer or real type, when the latter case would require me to limit my printout to a certain amount of digits?

长话短说，假设我们有以下示例:

Long story short, say we have the following example:

print("{0:.3f}".format(num)) # I cannot do print("{}".format(num))
                             # because I don't want all the decimals

是否有"Pythy"方法来确保例如如果 num == 1 我打印的是 1 而不是 1.000 (我的意思是除了用 if 声明)

Is there a "Pythy" way to ensure e.g. in case num == 1 that I print 1 instead of 1.000 (I mean other than cluttering my code with if statements)

推荐答案

对于Python 3 *，您只需使用 round() 因为除了舍入 float 外，当将其应用于整数时，它始终会返回诠释:

With Python 3*, you can just use round() because in addition to rounding floats, when applied to an integer it will always return an int:

>>> num = 1.2345
>>> round(num,3)
1.234
>>> num = 1
>>> round(num,3)
1

此行为记录在 help(float .__ round __)中:

Help on method_descriptor:

__round__(...)
    Return the Integral closest to x, rounding half toward even.
    When an argument is passed, work like built-in round(x, ndigits).

和 help(int .__ round __):

Help on method_descriptor:

__round__(...)
    Rounding an Integral returns itself.
    Rounding with an ndigits argument also returns an integer.

*在Python 2中， round()总是返回一个 float .

* With Python 2, round() always returns a float.

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