映射python字典中的值 [英] Mapping over values in a python dictionary
问题描述
{k1:v1,k2:v2 ...}
我想要得到 {k1:f(v1),k2 :f(v2)...}
如果我传递函数 f
。 有没有这样的内置功能?或者我需要在my_dictionary中为(k,v)执行
dict([(k,f(v) iteritems()])
理想情况下,我会写
my_dictionary.map_values(f)
或
my_dictionary.mutate_values_with(f)
也就是说,如果原始字典被突变或创建了副本,这并不重要。
没有这样的功能;这样做的最简单的方法是使用字母理解:
my_dictionary = {k:f(v)for k,v在my_dictionary.items())
在python 2.7中,使用 .iteritems ()
方法,而不是 .items()
来节省内存。直到python 2.7才引入了dict的理解语法。
请注意,列表上没有这样的方法;您必须使用列表解析或 map()
函数。
因此,您可以使用
my_dictionary的 map()
函数= dict(map(lambda(k,v):(k,f(v)),my_dictionary.iteritems()))
但这不是可读的,真的。
Given a dictionary { k1: v1, k2: v2 ... }
I want to get { k1: f(v1), k2: f(v2) ... }
provided I pass a function f
.
Is there any such built in function? Or do I have to do
dict([(k, f(v)) for (k, v) in my_dictionary.iteritems()])
Ideally I would just write
my_dictionary.map_values(f)
or
my_dictionary.mutate_values_with(f)
That is, it doesn't matter to me if the original dictionary is mutated or a copy is created.
There is no such function; the easiest way to do this is to use a dict comprehension:
my_dictionary = {k: f(v) for k, v in my_dictionary.items()}
In python 2.7, use the .iteritems()
method instead of .items()
to save memory. The dict comprehension syntax wasn't introduced until python 2.7.
Note that there is no such method on lists either; you'd have to use a list comprehension or the map()
function.
As such, you could use the map()
function for processing your dict as well:
my_dictionary = dict(map(lambda (k,v): (k, f(v)), my_dictionary.iteritems()))
but that's not that readable, really.
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