在Python列表中浮动偏差 [英] float deviation in python list
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问题描述
可能存在重复:
Python浮动 - str - 浮动怪异
我运行以下代码在codepad.org上的python:
num = 1.6
print num
list = [num ]
打印列表
num2 =列表[0]
打印num2
< p $>
1.6
[1.6000000000000001]
1.6
为什么在列表中的偏差很小?
解决方法
list .__ str __
调用 repr
$ c> str :
>>> str(1.6)
'1.6'
>>> repr(1.6)
'1.6000000000000001'
由于浮点数不能保证精确(对于整数a,b)不能表达为a * 2 b的值,则两个表示都是正确的,或换句话说:
>>> 1.6 == 1.6000000000000001
True
Possible Duplicate:
Python float - str - float weirdness
I run the following code in python on codepad.org:
num = 1.6
print num
list = [num]
print list
num2 = list[0]
print num2
And I get the following output:
1.6
[1.6000000000000001]
1.6
Why the tiny deviation in the list?
解决方案
list.__str__
calls repr
on its elements, where as print calls str
:
>>> str(1.6)
'1.6'
>>> repr(1.6)
'1.6000000000000001'
Since floating point numbers are not guaranteed to be exact (and cannot be exact for values that can't be expressed as a * 2b for integers a,b), both representations are correct, or, in other words:
>>> 1.6 == 1.6000000000000001
True
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