Python sequence and map unpacking operations

Unpacking is to extract each element of a sequence or map separately, and a simple use of a sequence unpacking is to extract the first or previous elements separately from the following elements, for example:

First, seconde, *rest = sequence

If there are at least three elements in the sequence, then after executing the above code, first = = Sequence[0], second = = Sequence[0], rest = = sequence[2:].

function receives indeterminate parameter

When the parameters of a function are indeterminate, you can use *args and **kwargs,*args without a key value, **kwargs has a key value.

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#!/usr/bin/python # -*- coding:utf-8 -*- importsys reload(sys) sys.setdefaultencoding(‘utf-8‘)   ‘‘‘ 当函数的参数不确定时，可以使用*args 和**kwargs，*args 没有key值，**kwargs有key值。   ‘‘‘  deffun_var_args_kwargs(data1, *args, **kwargs):     print‘data1:‘, type(data1), data1     print‘*args:‘, type(args), args     print‘**kwargs:‘, type(kwargs), kwargs   fun_var_args_kwargs(‘this is data1‘, 2, ‘3‘, 4.0, k1=‘value1‘, k2=‘value2‘)   print‘-------------‘  defprint_args(*args, **kwargs):     printargs.__class__.__name__, args, kwargs.__class__.__name__, kwargs   print_args() print_args(1, 2, 3, a=‘A‘)

Printing results:

123456

data1: <type‘str‘> this is data1 *args: <type‘tuple‘> (2, ‘3‘, 4.0) **kwargs: <type‘dict‘> {‘k2‘: ‘value2‘, ‘k1‘: ‘value1‘} ------------- tuple () dict {} tuple (1, 2, 3) dict {‘a‘: ‘A‘}

Python sequence and map unpacking operations