dict comprehension python 3

Learn how to operate Python dict () and learn python Many dict methods are similar to the list method. Here we will compare them with the list method. Nesting Nested in the list also exists, that is, the element is list. In dict, there are similar styles: >>> A_list = [[1, 2

From:http://www.cnblogs.com/yangyongzhi/archive/2012/09/17/2688326.htmlPython in Dict detailedpython3.0 above, the print function should be print () and there is no dict.iteritems () function.Writing Chinese comments in Python will cause an error, as long as you add # CODING=GBK to your head#字典的添加, delete, modify operationsDict = {"A": "Apple", "B": "Banana", "G": "Grape", "O": "Orange"}

python3.0 above, the print function should be print () and there is no dict.iteritems () function.Writing Chinese comments in Python will cause an error, as long as you add # CODING=GBK to your head#字典的添加, delete, modify operationsDict = {"A": "Apple", "B": "Banana", "G": "Grape", "O": "Orange"}dict["W"] = "Watermelon"Del (dict["a"])

calculate the location is called the Hash algorithm ). To ensure the correctness of the hash, the object as the key cannot be changed. In Python, strings, integers, and so on are immutable, so you can safely use them as keys. If the list is variable, it cannot be used as the key: >>> key = [1, 2, 3]>>> d[key] = 'a list'Traceback (most recent call last): File " ", line 1, in TypeError: unhashabl

variable B, it's easy to understand that variable a still points to the original string ' abc ', but the variable B points to the new string ' abc ': Therefore, for invariant objects, any method that invokes the object itself does not change the content of the object itself. Instead, these methods create new objects and return them, thus ensuring that immutable objects themselves are immutable.Summary Dict with Key-value storage structure is very

The Dict (or object) of Python and the conversion of JSON to each otherIn the Python language, the conversion between JSON data and dict dictionaries and objects is an essential operation.Bring your own JSON library in Python. by import json Importing.There are 2 methods in

and inserting is very fast and will not slow with the increase of key; It takes a lot of memory, and it wastes a lot of memory. And the list is the opposite: The time to find and insert increases as the element increases; Small footprint and little wasted memory. So, Dict is a way of exchanging space for time.Dict can be used in many places where high-speed lookups are needed, almost everywhere in

increase with the increase of key; It takes a lot of memory, and it wastes a lot of memory. And the list is the opposite: The time to find and insert increases as the element increases; Small footprint and little wasted memory. So, Dict is a way of exchanging space for time.Dict can be used in many places where high-speed lookups are needed, almost everywhere in Python code, it i

The sequence is the most basic data structure in Python. Each element in the sequence is assigned a number-its position, or index, the first index is 0, the second index is 1, and so on. Python has 6 built-in types of sequences, but the most common are lists and tuple tuples. Sequences can be performed by operations including indexing, slicing, adding, multiplying, and checking members. In addition,

DictPython built-in dictionary: dict support, Dict full name dictionary, in other languages also known as map, using key-value (Key-value) storage, with a very fast search speed.For example, suppose you want to find the corresponding score according to the name of the classmate, if you use list, you need two lists:names = ['Michael'Bob'Tracy ' = [[+]Given a name, to find the corresponding score, first to f

DictPython built-in dictionary: dict support, Dict full name dictionary, in other languages also known as map, using key-value (Key-value) storage, with a very fast search speed.For example, suppose you want to find the corresponding score according to the name of the classmate, if you use list, you need two lists:names = [‘Michael‘‘Bob‘‘Tracy‘]scores = [957585]Given a name, to find the corresponding score,