如何比较Django中的浮点值 [英] How to compare float value in in Django

问题描述

我需要比较我的项目中的浮点值我正在使用以下代码

Hi i need to compare the float value in my project i am using the folowing code

 if style_score.style_quiz_score ==float(17.40):

但它不适用于此，但是当我将值从17.40更改为17它可以正常工作，请告诉我如何比较浮点值

but it not works for this but when i change the value from 17.40 to 17 it works fine, please tell me how can i compare the float value

推荐答案

这是因为舍入误差。不要将浮点数与 == 进行比较，请始终使用此模板：

That's because of rounding errors. Never compare floats with ==, always use this template:

def floats_are_the_same(a,b): return abs(a-b) < 1e-6

if floats_are_the_same(value, 17.4):
    ....

ie检查该值是否关闭到某个所需的值。这是因为浮点运算几乎总是有四舍五入的错误：

i.e. check that the value is close to some desired value. This is because float arithmetic almost always has rounding errors:

>>> 17.1 + 0.3
17.400000000000002

另请参见：

See also: What is the best way to compare floats for almost-equality in Python?

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