Python common functions and modules

Originally from the blog Park and CSDN

1. Calculation function

ABS ()--Take absolute value

Max ()--take the maximum of the sequence, including list, tuple

Min ()--Take the minimum value of the sequence

Len ()--Take length

Divmod (A, B)---take a//b divisor integers and the remainder to become a tuple

Pow (x, y)--Take the Y power of X

Pow (x, y, z) is the power of X.

Round ()--Modify the accuracy, if not, default to 0 bits

Range () to quickly generate a list

2. Other functions

Callable ()--Returns whether callable returns True or False

Isinstance (A,type)---Determine whether the preceding is the type that follows, returns TRUE or False

CMP (A, B)---Determine if AB is equal, return 0,a<b return -1,a>b return 1

Range ()--quickly generate a list of types

Xrange ()---quickly generate a list of type xrange

3. type conversion function

Type ()

Int ()

Long ()

Float ()

Complex ()--Convert to negative

Hex ()--Convert to Hex

Oct ()--Convert to octal

Chr ()--parameter 0-252, returns the current ASCII code

Ord ()--The ASCII code of the parameter, returning the corresponding decimal integer

4.string function

Str.capitalize ()--capitalize the first letter of the string

Str.replace (A.B)---change string A to B

Str.split ()---Split the string, the first parameter is the delimiter, and the subsequent argument is split several times.

String function Import uses

5. Sequence functions

Filter ()--filters return to true return sequence

lambda--defining functions

The ZIP ()---compresses multiple lists into a new list, but if the number of elements in multiple lists is different, the combined results are grouped by the fewest elements

map--multiple lists to be compressed into a new list, but if the number of elements in multiple lists is different, the result is that all elements are taken out and the missing is replaced by none. If it is none, direct combination, if it is a function, can be combined by function

Reduce ()--the previous two execution functions for each element, followed by functions such as factorial, step plus, and subsequent elements

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UrlEncode and UrlDecode

When the URL contains Chinese or the parameter contains Chinese, the Chinese or special characters (/, &) need to be encoded for conversion.
The essence of UrlEncode: Convert the string to GBK encoding, and then replace the \x with%. If the terminal is UTF8 encoded, you need to turn the result into a UTF8 output, otherwise it will be garbled.

UrlEncode

The UrlEncode function inside the Urllib library can urlencode and convert the key and value of the Key-value health value to the a=1&b=2 string.

#key-value健值对>>> from urllib import urlencode>>> data={‘a‘:‘a1‘,‘b‘:‘中文‘}>>> print urlencode(data)a=a1&b=%E4%B8%AD%E6%96%87>>> data={‘a‘:‘a1‘,‘b测试‘:‘中文‘}>>> print urlencode(data)a=a1&b%E6%B5%8B%E8%AF%95=%E4%B8%AD%E6%96%87

The quote function inside the Urllib library can be UrlEncode converted to a single string.

#string>>> from urllib import quote>>> data="测试">>> print quote(data)%E6%B5%8B%E8%AF%95

UrlDecode

Urllib only provides the unquote () function.

>>> from urllib import unquote>>> unquote("%E6%B5%8B%E8%AF%95")‘\xe6\xb5\x8b\xe8\xaf\x95‘>>> print unquote("%E6%B5%8B%E8%AF%95")测试>>>

JSON processing

Two functions:

function	Description
Json.dumps	Encode a Python object as a JSON string (Object---string)
Json.loads	Decodes an encoded JSON string into a Python object (string--object)

Json.dumps

Syntax: Json.dumps (data, Sort_keys=true, indent=4,separators= (Self.item_separator, Self.key_separator))

>>> Import JSON>>> data={A:"A1", "B" : "B1"} >>> jsonstr=json.dumps (data) >>> print jsonstr{< Span class= "hljs-string" > "a" :  "A1",  "B" :  "B1"}  #输出格式化 >>> print json.dumps (data, Sort_keys=true, Indent=4,separators= ( ","  "a" : "A1",  "B" : "B1"} >>>             

The conversion table of the Python primitive type to JSON type:

Python	JSON
Dict	Object
List,tuple	Array
Str,unicode	String
Int,long,float	Number
True	True
False	False
None	Null

Json.loads

json.loads--returns the data type of the Python field

>>>Import JSON>>> jsonstr=' {' A ': ' A1 ', ' B ': ' B1 '} '>>>Print Json.loads (JSONSTR) {U ' A ':U ' A1 ',U ' B ':U ' B1 '}>>> jsonstr=' {' A ': ' A1 ', ' B ': null, ' C ': false, ' d ': {' AA ': ' Aa1 ', ' BB ': ' BB1 '} '>>> Print json.loads (jsonstr) {u ' a ': u ' A1 ', U ' C ': False, u ' B ': None, u ' d ': {u ' AA ': u ' aa1 ', u ' bb ': u ' bb1 '}}>>> jsonstr=' [{"A": "A1"},{"B": "B2"}] '  >>> Print json.loads (jsonstr) [{u ' a ': u ' A1 '}, {u ' B ': u ' B2 '}]   

JSON type conversion to Python type comparison table

JSON	Python
Object	Dict
Array	List
String	Unicode
Number (int)	Int,long
Number (real)	Float
True	True
False	False
Null	None

Conclusion: Print only outputs Python-recognized data types, and python.dumps can format the output.

Computes the string MD5

Method One: Use the MD5 package

Import MD5 def calMd5 (signdata,signkey,joiner=""):    signdata=signdata+joiner+""+ Signkey    m=md5.new (signdata)    = m.hexdigest ()    return sign

Method Two: Use the Hashlib package

Import Hashlib def calHashMd5 (signdata,signkey,joiner=""):    signdata=signdata+joiner+"" +Signkey    m=hashlib.md5 (signdata)    = m.hexdigest ()    return Sign

Calculate HMACSHA1

HMAC: Key-related hash operation message authentication code, the HMAC operation takes advantage of a hashing algorithm (either MD5 or SHA-1), with a key and a message as input, generating a message digest as output.

Role:
(1) Verifying the accepted authorization data and authentication data;
(2) Confirm that the received command request is an authorized request and that the transfer process has not been tampered with

Import HMAC Import Base64 def hmacsha1withbase64 (signdata,signkey):     = hmac.new (Signkey, SIGNDATA,SHA1). Digest ()    = base64.b64encode (sign)    return Sign

string concatenation

 fromCollectionsImportordereddictdefComposestr (data,joiner,withkey=true,key_value_joiner="="): Data= Ordereddict (sorted (Data.items (), key=Lambdat:t[0])) ifWithkey:signdata= Joiner.join ([Key_value_joiner.join (str (key), str (elem)) forKey, EleminchData.iteritems ()]) Else: SignData= Joiner.join ([elem forKey, EleminchData.items ()]) returnSignData

Python common functions and modules