What is pack and unpack in python?
We use two operators * (for tuples) and ** (for dictionaries). Show Background Python3
Output : TypeError: fun() takes exactly 4 arguments (1 given) Python3
Output : (1, 2, 3, 4) We need to keep in mind that the no. of arguments must be the same as the length of the list that we are unpacking for the arguments. Python3
Output: Traceback (most recent call last): File "/home/592a8d2a568a0c12061950aa99d6dec3.py", line 10, in As another example, consider the built-in range() function that expects separate start and stops arguments. If they are not available separately, write the function call with the *-operator to unpack the arguments out of a list or tuple: Python3
Packing Python3
Output: 15 30 The above function mySum() does ‘packing’ to pack all the arguments that this method call receives into one single variable. Once we have this ‘packed’ variable, we can do things with it that we would with
a normal tuple. args[0] and args[1] would give you the first and second argument, respectively. Since our tuples are immutable, you can convert the args tuple to a list so you can also modify, delete, and re-arrange items in i. Packing and Unpacking Python3
Output: (Geeksforgeeks, awesome, world!) ** is used for dictionaries Python3
Output: 2 4 10 Here ** unpacked the dictionary used with it, and passed the items in the dictionary as keyword arguments to the function. So writing “fun(1, **d)” was equivalent to writing “fun(1, b=4, c=10)”. Python3
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Applications and Important Points
Reference : What is packing and unpacking?The pack function takes a list of values to be packed as a second argument and returns a scalar character string containing the packed values. The unpack function takes a character string containing the values to be unpacked as a second argument, and returns a list of individual values extracted from the string.
What is packing in Python?Practical Data Science using Python
Above operation is called 'packing” as it pack all the arguments into one single variable that this method call receives into a tuple called args. We can use name other than args, but args is the most common and pythonic way of doing things.
What is packing and unpacking in tuples?In another way, it is called unpacking of a tuple of values into a variable. In packing, we put values into a new tuple while in unpacking we extract those values into a single variable.
What is unpack operator in Python?Both * and ** are the operators that perform packing and unpacking in Python. The * operator (quite often associated with args) can be used with any iterable (such as a tuple, list and strings), whereas the ** operator, (quite often associated with kwargs) can only be used on dictionaries.
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