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更新时间：2022-10-21 23:31:15
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 。
float $ c>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]
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]