如何在Python中将已定义的字典传递给** kwargs? [英] How can I pass a defined dictionary to **kwargs in Python?

问题描述

这是我第一次在这里发帖.希望我能得到很好的建议:)我学习了如何将 ** kwargs 和 * args 都传递给函数，并且效果很好，如下所示:

This is my first time posting here. Hopefully I can get nice advice:) I learned how to pass both **kwargs and *args into a function, and it worked pretty well, like the following:

def market_prices(name, **kwargs):
     print("Hello! Welcome to "+name+" Market!")
     for fruit, price in kwargs.items():
         price_list = " {} is NTD {} per piece.".format(fruit,price)
         print (price_list) 
market_prices('Wellcome',banana=8, apple=10)

但是，在实际情况下，我宁愿预定义具有很多键和值的字典，因此在调用函数时不必输入所有参数.我已经在网上搜索过，但找不到很好的例子或解释:/你能给我一些建议吗?这是我尝试利用的代码:

However in real case, I'd rather pre-defined a dictionary with lots of key&value, so I won't don't have to type in every parameter when calling my function. I have searched online but cannot find a good example or explanation:/ Could you give me some advice? Here is the code I try to utilize:

fruits:{"apple":10,
       "banana":8,
       "pineapple":50,
       "mango":45
       }

def market_prices(name, **fruits):
    print("Hello! Welcome to "+name+" Market!")
    for fruit, price in fruits.items():
        price_list = " {} is NTD {} per piece.".format(fruit,price)
        print (price_list)

market_prices('Wellcome ', fruits)

NameError:未定义名称水果"

NameError: name 'fruits' is not defined

非常感谢您！:)

推荐答案

有 4 种可能的情况:

There are 4 possible cases:

您使用命名参数调用该函数，并希望在该函数中使用命名变量:
(请注意默认值)

You call the function using named arguments and you want named variables in the function:
(note the default values)

def buy(orange=2, apple=3):
    print('orange: ', orange)
    print('apple: ', apple)

buy(apple=4)
# orange:  2
# apple:  4

您使用命名参数调用该函数，但是您希望在该函数中使用字典:
然后在函数定义中使用 ** dictionaryname 来收集传递的参数

You call the function using named arguments but you want a dictionary in the function:
then use **dictionaryname in the function definition to collect the passed arguments

def buy(**shoppinglist):
    for name, qty in shoppinglist.items():
        print('{}: {}'.format(name, qty) )

buy(apple=4, banana=5)
# banana: 5
# apple: 4

您通过字典调用该函数，但是您希望在该函数中使用命名变量:
调用函数以解压缩字典时，请使用 ** dictionaryname

You call the function passing a dictionary but you want named variables in the function:
use **dictionaryname when calling the function to unpack the dictionary

def buy(icecream=1, apple=3, egg=1):
    print('icecream:', icecream)
    print('apple:', apple)
    print('egg:', egg)

shoppinglist = {'icecream':5, 'apple':1}
buy(**shoppinglist)
# icecream: 5
# apple: 1
# egg: 1

您调用传递字典的函数，并希望在该函数中字典:
只需通过字典

You call the function passing a dictionary and you want a dictionary in the function:
just pass the dictionary

def buy(shoppinglist):
    for name, qty in shoppinglist.items():
        print('{}: {}'.format(name, qty) )

shoppinglist = {'egg':45, 'apple':1}
buy(shoppinglist)
# egg: 45
# apple: 1

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