在蟒蛇漂浮容易漂亮的打印？ [英] Easy pretty printing of floats in python?

问题描述

我有一个浮动列表。如果我简单地 print ，它会显示如下：

  [ 9.0，0.052999999999999999，0.032575399999999997，0.010892799999999999，0.055702500000000002，0.079330300000000006] 
  

我可以使用打印％.2f，这要求循环遍历列表，但是这对于更复杂的数据结构。
我喜欢这样的东西（我完全是这样做的）

 >>> import print_options 
>>> print_options.set_float_precision（2）
>>>打印[9.0，0.052999999999999999，0.032575399999999997，0.010892799999999999，0.055702500000000002，0.079330300000000006] 
 [9.0,0.05,0.03,0.01,0.06,0.08] 
  

解决方案

更长期的解决方案是子类 float ：

 >>> （漂浮）：
 def __repr __（self）：
 return％0.2f％self 
 
>>> x 
 [1.290192，3.0002，22.119199999999999，3.4110999999999998] 
>>> x = map（prettyfloat，x）
>>> x 
 [1.29,3.00,22.12,3.41] 
>>> y = x [2] 
>>> y 
 22.12 
  

子类化的问题 float 是它破坏了显式查找变量类型的代码。但据我所知，这是唯一的问题。并且一个简单的 x = map（float，x）将取消转换为 prettyfloat 。

悲惨的是，你不能只是因为 float 如果你不想子类 float ，但是不介意定义一个函数， map（f，x）比 [f（n）for n in x]简洁得多

I have a list of floats. If I simply print it, it shows up like this:

[9.0, 0.052999999999999999, 0.032575399999999997, 0.010892799999999999, 0.055702500000000002, 0.079330300000000006]

I could use print "%.2f", which would require a for loop to traverse the list, but then it wouldn't work for more complex data structures. I'd like something like (I'm completely making this up)

>>> import print_options
>>> print_options.set_float_precision(2)
>>> print [9.0, 0.052999999999999999, 0.032575399999999997, 0.010892799999999999, 0.055702500000000002, 0.079330300000000006]
[9.0, 0.05, 0.03, 0.01, 0.06, 0.08]

解决方案

A more permanent solution is to subclass float:

>>> class prettyfloat(float):
    def __repr__(self):
        return "%0.2f" % self

>>> x
[1.290192, 3.0002, 22.119199999999999, 3.4110999999999998]
>>> x = map(prettyfloat, x)
>>> x
[1.29, 3.00, 22.12, 3.41]
>>> y = x[2]
>>> y
22.12

The problem with subclassing float is that it breaks code that's explicitly looking for a variable's type. But so far as I can tell, that's the only problem with it. And a simple x = map(float, x) undoes the conversion to prettyfloat.

Tragically, you can't just monkey-patch float.__repr__, because float's immutable.

If you don't want to subclass float, but don't mind defining a function, map(f, x) is a lot more concise than [f(n) for n in x]

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