Python 将分数转换为小数
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Python Convert fraction to decimal
提问by Kartik
I want to convert 1/2 in python so that when i say print x (where x = 1/2) it returns 0.5
我想在 python 中转换 1/2，这样当我说 print x (where x = 1/2) 它返回 0.5
I am looking for the most basic way of doing this, without using any split functions, loops or maps
我正在寻找这样做的最基本的方法，而不使用任何拆分函数、循环或映射
I have tried float(1/2) but I get 0... can someone explain me why and how to fix it?
我试过 float(1/2) 但我得到 0 ... 有人可以解释我为什么以及如何解决它吗？
Is it possible to do this without modifying the variable x= 1/2 ??
是否可以在不修改变量 x= 1/2 的情况下做到这一点？？
Thanks
谢谢
采纳答案by Ant
in python 3.x any division returns a float;
在 python 3.x 中，任何除法都返回一个浮点数；
>>> 1/2
0.5
to achieve that in python 2.x, you have to force float conversion:
要在 python 2.x 中实现这一点，您必须强制进行浮点转换：
>>> 1.0/2
0.5
or to import the division from the "future"
或从“未来”导入分区
>>> from __future__ import division
>>> 1/2
0.5
An extra: there is no a built-in fraction type, but there is in the official library:
额外的：没有内置的分数类型，但在官方库中有：
>>> from fractions import Fraction
>>> a = Fraction(1, 2) #or Fraction('1/2')
>>> a
Fraction(1, 2)
>>> print a
1/2
>>> float(a)
0.5
and so on...
等等...
回答by Greg Hewgill
You're probably using Python 2. You can "fix" division by using:
您可能正在使用 Python 2。您可以使用以下方法“修复”除法：
from __future__ import division
at the start of your script (before any other imports). By default in Python 2, the /operator performs integer division when using integer operands, which discards fractional parts of the result.
在脚本的开头（在任何其他导入之前）。默认情况下，在 Python 2 中，/运算符在使用整数操作数时执行整数除法，这会丢弃结果的小数部分。
This has been changed in Python 3 so that /is always floating point division. The new //operator performs integer division.
这在 Python 3 中已更改，因此/始终是浮点除法。new//运算符执行整数除法。
回答by CaptainChristo
Alternatively, you can force floating point division by specifying a decimal or by multiplying by 1.0. For instance (from inside the python interpreter):
或者，您可以通过指定小数或乘以 1.0 来强制进行浮点除法。例如（从python解释器内部）：
>>> print 1/2
0
>>> print 1./2
0.5
>>> x = 1/2
>>> print x
0
>>> x = 1./2
>>> print x
0.5
>>> x = 1.0 * 1/2
>>> print x
0.5
EDIT: Looks like I was beaten to the punch in the time it took to type up my response :)
编辑：看起来我在输入我的回复时受到了打击:)
回答by Karl Knechtel
There is no quantity 1/2anywhere. Python does not represent rational numbers with a built-in type - just integers and floating-point numbers. 1 is divided by 2 - following the integer division rules - resulting in 0. float(0)is 0.
1/2任何地方都没有数量。Python 不使用内置类型表示有理数——只是整数和浮点数。1 除以 2 - 遵循整数除法规则 - 结果为 0。float(0)就是 0。
回答by Brian Minton
If the input is a string,then you could use Fraction directly on the input:
如果输入是字符串，则可以直接在输入上使用 Fraction ：
from fractions import Fraction
x='1/2'
x=Fraction(x) #change the type of x from string to Fraction
x=float(x) #change the type of x from Fraction to float
print x
