JSON, pickle, random, Hashlib, collections for Python's common modules

1. JSON and Pickle

JSON is used to convert between string and Python data types
Pickle is used to convert between Python-specific types and Python data types
There are four methods available for both JSON and Pickle dumps,dump,loads,load

 ##json Dumps ()##转换成字符串Loads ()##将json编码的字符串再转换为python的数据结构Dump ()##转换成字符串并存存储到文件中Load ()##从数据文件中读取数据 and convert the JSON-encoded string into a Python data structure>>>Print(Json.dumps (['AA','BB','cc']))["AA","BB","cc"]>>>Print(Json.loads ('["AA", "BB", "CC"]'))['AA','BB','cc'] ##pickle Dumps ()##将数据通过特殊的形式转换为只有python语言认识的字符串Loads ()##将pickle数据转换为python的数据结构Dump ()##将数据通过特殊的形式转换为只有python语言认识的字符串, and write the fileLoad ()##从数据文件中读取数据, and convert to Python data structure>>>Print(Pickle.dumps (['AA','BB','cc'])) b'\x80\x03]q\x00 (x\x02\x00\x00\x00aaq\x01x\x02\x00\x00\x00bbq\x02x\x02\x00\x00\x00ccq\x03e.'>>>Print(Pickle.loads (b'\x80\x03]q\x00 (x\x02\x00\x00\x00aaq\x01x\x02\x00\x00\x00bbq\x02x\x02\x00\x00\x00ccq\x03e.'))['AA','BB','cc']

2. Random

Random.random ()#a random decimal between #0Random.uniform (1,3)#random decimal between #1 toRandom.randint (1,5)#a random integer between #[1,5]Random.randrange (1,10,2)##[1,10) random odd number, interval of 2Random.choice ([1,' at', [4,5]])##随机选择一个返回Random.sample ([1,' at', [4,5]],2]##随机选择多个返回, the number returned is the second argument of the functionRandom.shuffle ([1,3,5,7,9])##打乱列表顺序# #返回验证码ImportRandomdefv_code (): Code="'     forIinchRange (5): Num=random.randint (0,9) Alf=CHR (Random.randint (65,90)) Add=Random.choice ([num,alf]) code="". Join ([Code,str (add)])returnCodePrint(V_code ())

3, Hashlib

Hashlib provides a common digest algorithm, such as MD5,SHA1 and so on.

##md5计算MD5 = HASHLIB.MD5 ("Key". Encode ("UTF8"))##可以添加秘钥, the secret key can be a user ID, so even if the password is the same, the MD5 after the encryption is not the sameMd5.update (b'Love Fly')Print(Md5.hexdigest ())##SHA1SHA1 = HASHLIB.SHA1 ("Key". Encode ("UTF8")) Sha1.update (b'Love Fly')Print(Sha1.hexdigest ())##计算MD5>>>ImportHashlib>>> MD5 =hashlib.md5 ()>>> Md5.update (b'Love Fly')>>>Print(Md5.hexdigest ()) 61976ec704dbce25ccb37ecacef1e4d6##如果数据量很大, you can call Update () multiple times in chunks, and the result is the same as the final calculation>>>ImportHashlib>>> MD5 =hashlib.md5 ()>>> Md5.update (b' Love')>>> Md5.update (b'Fly')>>>Print(Md5.hexdigest ()) 61976ec704dbce25ccb37ecacef1e4d6

4, collections

Ollections is a python built-in collection module that provides a number of useful collection classes and is a complement to the default data structure of Python

##namedtuple是一个函数, it is used to create a custom tuple object, and it specifies the number of tuple elements, and you can refer to an element of a tuple using a property rather than an index. >>> fromCollectionsImportNamedtuple>>> colltuple = Namedtuple ('Colltuple', ['x','y'])>>> col = colltuple ('Yong','Fly')>>>col.x'Yong'>>>Col.y'Fly'based on the built-in data types (dict, list, set, tuple), the collections module also provides several additional data types: Counter, deque, Defaultdict, Namedtuple and Ordereddict and so on. 1. Namedtuple: Generates a tuple that can use a name to access the content of an element2. Deque: Double-ended queue that can quickly append and eject objects from the other side3. Counter: Counter, mainly used to count4. Ordereddict: Ordered dictionary5. Defaultdict: Dictionary with default values##deque: The list inserts and deletes elements are slow and the data volume is large, and insertions and deletions are inefficient. Deque is a two-way list for efficient insert and delete operations, suitable for queues and stacks. >>> fromCollectionsImportdeque>>> q = deque (['a','b','C'])>>> Q.append ('D')##默认添加列表最后一项>>> Q.appendleft ('e')##添加到列表第一项>>>Qdeque (['e','a','b','C','D'])>>> Q.pop ()##默认删除列表最后一个元素'D'>>> Q.popleft ()##删除列表的第一个元素'e'>>>Qdeque (['a','b','C'])##defaultdict使用字典时, if the referenced key does not exist, it throws Keyerror, and if you want the key to be absent, return a default value, you can use Defaultdict.X=defaultdict (Lambda:'N /A')##OrderedDict有序字典的应用. The order of the ordereddict is in the order in which they are inserted, not in the key. ##Counter简单的计数器, for example, the number of occurrences of a statistical character. 

JSON, pickle, random, Hashlib, collections for Python's common modules