kwargs | 易学教程

Passing a list of kwargs?

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问题 Can I pass a list of kwargs to a method for brevity? This is what i'm attempting to do: def method(**kwargs): #do something keywords = (keyword1 = 'foo', keyword2 = 'bar') method(keywords) 回答1: Yes. You do it like this: def method(**kwargs): print kwargs keywords = {'keyword1': 'foo', 'keyword2': 'bar'} method(keyword1='foo', keyword2='bar') method(**keywords) Running this in Python confirms these produce identical results: {'keyword2': 'bar', 'keyword1': 'foo'} {'keyword2': 'bar', 'keyword1'

Converting Python dict to kwargs?

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I want to build a query for sunburnt(solr interface) using class inheritance and therefore adding key - value pairs together. The sunburnt interface takes keyword arguments. How can I transform a dict ({'type':'Event'}) into keyword arguments (type='Event') ? unutbu Use the double-star (aka double-splat? ) operator: func(**{'type':'Event'}) is equivalent to func(type='Event') ** operator would be helpful here. ** operator will unpack the dict elements and thus **{'type':'Event'} would be treated as type='Event' func(**{'type':'Event'}) is same as func(type='Event') i.e the dict elements would

Why use **kwargs in python? What are some real world advantages over using named arguments?

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问题 I come from a background in static languages. Can someone explain (ideally through example) the real world advantages of using **kwargs over named arguments ? To me it only seems to make the function call more ambiguous. Thanks. 回答1: Real-world examples: Decorators - they're usually generic, so you can't specify the arguments upfront: def decorator(old): def new(*args, **kwargs): # ... return old(*args, **kwargs) return new Places where you want to do magic with an unknown number of keyword

In Python, what determines the order while iterating through kwargs?

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问题 In python, I wrote this function to teach myself how **kwargs works in Python: def fxn(a1, **kwargs): print a1 for k in kwargs: print k, " : ", kwargs[k] I then called this function with fxn(3, a2=2, a3=3, a4=4) Here was the output that my Python interpreter printed: 3 a3 : 3 a2 : 2 a4 : 4 Why did the for loop print the value of a3 before that of a2 even though I fed a2 into my function first? 回答1: kwargs is a dictionary. Dictionaries are unordered - simply put, the order is unspecified and

Proper way to use **kwargs in Python

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What is the proper way to use **kwargs in Python when it comes to default values? kwargs returns a dictionary, but what is the best way to set default values, or is there one? Should I just access it as a dictionary? Use get function? class ExampleClass: def __init__(self, **kwargs): self.val = kwargs['val'] self.val2 = kwargs.get('val2') A simple question, but one that I can't find good resources on. People do it different ways in code that I've seen and it's hard to know what to use. You can pass a default value to get() for keys that are not in the dictionary: self.val2 = kwargs.get('val2',

Converting Python dict to kwargs?

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问题 I want to build a query for sunburnt(solr interface) using class inheritance and therefore adding key - value pairs together. The sunburnt interface takes keyword arguments. How can I transform a dict ({\'type\':\'Event\'}) into keyword arguments (type=\'Event\') ? 回答1: Use the double-star (aka double-splat?) operator: func(**{'type':'Event'}) is equivalent to func(type='Event') 回答2: ** operator would be helpful here. ** operator will unpack the dict elements and thus **{'type':'Event'} would

Calling a Python function with *args,**kwargs and optional / default arguments

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问题 In python, I can define a function as follows: def func(kw1=None,kw2=None,**kwargs): ... In this case, i can call func as: func(kw1=3,kw2=4,who_knows_if_this_will_be_used=7,more_kwargs=Ellipsis) I can also define a function as: def func(arg1,arg2,*args): ... which can be called as func(3,4,additional,arguments,go,here,Ellipsis) Finally, I can combine the two forms def func(arg1,arg2,*args,**kwargs): ... But, what does not work is calling: func(arg1,arg2,*args,kw1=None,kw2=None,**kwargs):

What is the purpose and use of **kwargs?

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问题 What are the uses for **kwargs in Python? I know you can do an objects.filter on a table and pass in a **kwargs argument. Can I also do this for specifying time deltas i.e. timedelta(hours = time1) ? How exactly does it work? Is it classes as \'unpacking\'? Like a,b=1,2 ? 回答1: You can use **kwargs to let your functions take an arbitrary number of keyword arguments ("kwargs" means "keyword arguments"): >>> def print_keyword_args(**kwargs): ... # kwargs is a dict of the keyword args passed to

Use of *args and **kwargs [duplicate]

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问题 This question already has an answer here: What does ** (double star/asterisk) and * (star/asterisk) do for parameters? 19 answers So I have difficulty with the concept of *args and **kwargs . So far I have learned that: *args = list of arguments - as positional arguments **kwargs = dictionary - whose keys become separate keyword arguments and the values become values of these arguments. I don\'t understand what programming task this would be helpful for. Maybe: I think to enter lists and