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1. Array

Print (a) # how to create a listL1 = [] print (type (L1)) print (L1) L2 = [1, 2, 3, 5, 9, 0] print (L2) # add L2.append (11) # insert into the last value print (L2) # add to the specified position, insert (insert into what data) other data will move one position to the right # each value in list The location they are in is called the subscript. The id starts from left to right and starts from 0. L2.insert (2Magne13) print (L2) # deletion # remove is deleted through the value, and the first value found from left to right is deleted # if the value does not exist Report exception L2.remove (0) print ("=") print (L2) print (L2.pop (4)) print (L2) # change L2 [1] = '111 query # look up print (L2 [1]) print (L2 [3]) print (L2 [6]) # traversal list data query for i in L2:print ("current element:", I)

two。 Array common function

Len (list)

Number of list elements

Max (list)

Returns the maximum value of the list element

Min (list)

Returns the minimum value of a list element

List (seq)

Convert tuples to lists

List.append (obj)

Add a new object at the end of the list

List.count (obj)

Count the number of times an element appears in the list

List.extend (seq)

Append multiple values from another sequence at the end of the list at once (extend the original list with the new list)

List.index (obj)

Find out the index position of the first match of a value from the list

List.insert (index, obj)

Insert objects into the list

List.pop ([index=-1])

Removes an element from the list (the default last element) and returns the value of that element

List.remove (obj)

Remove the first occurrence of a value in the list

List.reverse ()

Elements in reverse list

List.sort (key=None, reverse=False)

Sort the original list

List.clear ()

Clear the list

List.copy ()

Copy list

3. Common string function

Capitalize ()

Converts the first character of a string to uppercase

Center (width, fillchar)

Returns a string with the specified width centered by width. Fillchar is a padded character and defaults to a space.

Count (str, beg= 0 (string))

Returns the number of str occurrences in string, or the number of str occurrences within the specified range if specified by beg or end

Bytes.decode (encoding= "utf-8", errors= "strict")

There is no decode method in Python3, but we can use the decode () method of the bytes object to decode the given bytes object, which can be encoded and returned by str.encode ().

Encode (encoding='UTF-8',errors='strict')

Encode a string in the encoding format specified by encoding. If there is an error, an exception of ValueError is reported by default, unless errors specifies' ignore' or 'replace'.

Endswith (suffix, beg=0, end=len (string))

Check whether the string ends with obj, and if beg or end is specified, check whether the specified range ends with obj. If so, return True, otherwise return False.

Expandtabs (tabsize=8)

Convert the tab symbol in the string string to spaces, and the default number of spaces for the tab symbol is 8.

Find (str, beg=0, end=len (string))

Check whether str is contained in a string, if you specify a range of beg and end, check whether it is included in the specified range, and return-1 if it contains the index value that returns the start.

Index (str, beg=0, end=len (string))

Just like the find () method, except that an exception is reported if the str is not in the string.

Isalnum ()

Return True if the string has at least one character and all characters are letters or numbers, otherwise return False

Isalpha ()

Return True if the string has at least one character and all characters are letters or Chinese characters, otherwise return False

Isdigit ()

Return True if the string contains only numbers, otherwise return False..

Islower ()

If the string contains at least one case-sensitive character, and all these (case-sensitive) characters are lowercase, True is returned, otherwise False is returned

Isnumeric ()

Returns True if the string contains only numeric characters, otherwise returns False

Isspace ()

Returns True if the string contains only whitespace, or False.

Istitle ()

Returns True if the string is themed (see title ()), otherwise returns False

Isupper ()

Returns True if the string contains at least one case-sensitive character, and all these (case-sensitive) characters are uppercase, otherwise returns False

Join (seq)

Merges all elements (string representation of) in seq into a new string with the specified string as the delimiter

Len (string)

Returns the string length

Ljust (width [, fillchar])

Returns a new string that is left-aligned and populated with fillchar to the length width. Fillchar defaults to spaces.

Lower ()

Converts all uppercase characters in a string to lowercase.

Lstrip ()

Truncates the space to the left of the string or the specified character.

Maketrans ()

Create a conversion table for character mapping. for the easiest way to accept two parameters, the first parameter is a string, which represents the character to be converted, and the second parameter is the string that represents the target of the conversion.

Max (str)

Returns the largest letter in the string str.

Min (str)

Returns the smallest letter in the string str.

Replace (old, new [, max])

Replace the old in the string with new, or no more than max times if specified by max.

Rfind (str, beg=0,end=len (string))

Similar to the find () function, but starting from the right.

Rindex (str, beg=0, end=len (string))

Similar to index (), but starting on the right.

Rjust (width, [, fillchar])

Returns a new string that is right-aligned and populated with fillchar (the default space) to the length width

Rstrip ()

Removes the space at the end of a string.

Split (str= "", num=string.count (str))

Use str as the delimiter to intercept strings. If num has a specified value, only num+1 substrings are intercepted.

Splitlines ([keepends])

A list containing lines as elements is returned, separated by lines ('\ r','\ r\ n',\ n'). If the parameter keepends is False, there is no newline character, if it is True, the newline character is retained.

Startswith (substr, beg=0,end=len (string))

Checks whether the string begins with the specified substring substr, returns True if so, returns False otherwise. If beg and end specify values, they are checked within the specified range.

Strip ([chars])

Execute lstrip () and rstrip () on the string

Swapcase ()

Convert uppercase to lowercase and lowercase to uppercase in a string

Title ()

Returns a "titled" string, which means that all words start with uppercase and the rest are lowercase (see istitle ())

Translate (table, deletechars= "")

Convert the characters of string according to the table given by str (containing 256characters), and put the characters to be filtered into the deletechars parameter

Upper ()

Convert lowercase letters in a string to uppercase

Zfill (width)

Returns a string of length width, with the original string aligned to the right, preceded by a 0

Isdecimal ()

Check whether the string contains only decimal characters, and if it returns true, otherwise it returns false.

'1. String constant set 'import stringprint (string.ascii_uppercase) # uppercase letter print (string.ascii_lowercase) # lowercase letter print (string.ascii_letters) # uppercase and lowercase letter print (string.digits) # numeric print (string.punctuation) # symbol set print (string.printable) # input word matching set, including uppercase and lowercase alphanumeric and symbol set' 2. String case conversion 5 'stringed worldletters print (str.capitalize ()) # only the first letter uppercase, Hellojournal worldletters print (str.title ()) # only the first letter of each word is uppercase, Hellojournal Worldword print (str.upper ()) # each letter is uppercase, helloreWorldprint (str.lower ()) # each letter is lowercase, hellomWorldprint (str.swapcase ()) # is case swapped HELLOL WORLDELECTIVE 3. The content of the string determines whether the characters in the 10 'num='123'alp='asd'num_alp='a1s2d'printable=' `~! @ # $%' print (num.isdigit ()) # string are all numbers, whether the characters in the Trueprint (alp.isalpha ()) # string are all letters, and whether the characters in the Trueprint (num_alp.isalnum ()) # string are all letters and numbers Whether the characters in the Trueprint (printable.isprintable ()) # string are all input characters, whether the characters in the Trueprint (num.isnumeric ()) # string are all numbers, whether the characters in the Trueprint (alp.islower ()) # string are all lowercase letters, and whether the characters in the Trueprint (num_alp.isupper ()) # string are all uppercase letters. The characters in the Falseprint (alp.istitle ()) # string are shaped like whether the characters in the title Hello World,Falseprint (''. Isspace ()) # string are all spaces, and whether the characters in the Trueprint ('ha '.isascii ()) # string can be represented by ascll codes. Chinese characters are encoded by Unicode, so they are False'4. Fill the string with 'str='Welcome'print (str.center (13 lemons)) # * Welcome***print (str.ljust (10 lemons)) # Welcome+++print (str.rjust (10) #-Welcomeprint (str.zfill (10)) # 000Welcomeprint ('-100'.zfill (10)) #-000000100print ('+ 100'.zfill (10)) # + 000000100R5. If there is a substring in 'str='awasdhiwhhihuasd~hjdsasdihfi'print (str.index (' asd')) # str, the index value of the self-paid index will be returned. If it does not exist, an error try: print (str.index ('aes')) except ValueError as v: print (v) print (str.find (' asd')) # str will be returned if there is a substring. If it does not exist, return-1print (str.find ('aes')) print (str.count (' asd')) # return the number of substrings contained in the string print (str.count ('aes')) # if it does not exist, return 0string 6. The string replaces' stringy characters hellogramme worldview printed (str.replace ('world','python')) # to generate a copy of the replacement character, hello,python! The original string str did not change the print (str) # Hellograd Worldwide worldviews stringency printing awasdhihihuasdcharacters hjdsasdihfights print (str.replace ('asd','ASD',2)) # awASDhiwhhihuASD~hjdsasdihfi'7. The string addition'# join () method is used to generate a new string from the elements in the sequence with the specified character concatenation # usage: str.join (sequence), sequence includes strings, lists, meta-ancestors, collections and dictionaries (dictionaries connect only key), where the elements of lists, meta-ancestors and collections must be strings, otherwise an error lis= will be reported. Print (''.join (lis)) # I am IronManning print (' * '.join ({' 1mm ABCD' 2'})) print ('- '.join (' ABCD')) print ('+ '.join (' axie pr é c') print ('~ '.join ({' axiaxianghuanghuan2}))'8. String pruning'b = "qq-qeasdzxcrtqwe----" print (b.strip ('q')) #-qeasdzxcrtqwe----'9. String cut'b = "this is string example" print (b.split ('')) # slice ['this',' is', 'string']' 9 with a space as a separator. String cutting''partition (sep) cuts a given string into three parts. First, the string sep is searched, the part before sep is a part, sep itself is a part, and the rest as a part is very similar between partition () and rpartition (). The main difference is that when sepsis is not specified in the string, partition () is divided into three parts, string, blank, blank rpartition () is divided into three parts White space, string''test='haoiugdsgfasdhreiuufufg'print (test.partition (' asd')) # ('haoiugdsgf',' asd', 'hreiuufufg') print (test.partition (' nji')) # ('haoiugdsgfasdhreiuufufg',','') print (test.rpartition ('njj')) # (',', 'haoiugdsgfasdhreiuufufg')

4. Format string

Formatting strings can help us to output what we want, and it is also very convenient to use, mainly in the following forms.

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# formatting string

Print ('hello, {0} {1} {2}'. Format ('zhong',' yuan', 'gong')) # formatted by location

Print ('hello, {name}, my name is {self}!'. Format (name = 'tom', self =' sir')) # filled with key

L = ['tom',' sir']

Print ('hello, {l [0]}, my name is {l [1]}!'. Format (l = l) # is populated by the subscript of the array

M = {'name':' tom', 'self':' sir'}

Print ('hello, {m [name]}, my name is {m [self]}!'. Format (m = m) # is filled with key in the dictionary, and the key name is not in quotation marks

The output above is: hello,tom,my name is sirical!

five. String case problem

With regard to the case conversion of English strings, you can use the following functions

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# initials capitalized

A = 'hello,zHong yUan GONG GOGG GOGGONGOGONGONGOGOGONGONGONGONGONGONGOGONGOGOG

Print (a.title ())

# all uppercase

Print (a.upper ())

# all lowercase

Print (a.lower ())

# capital the first letter of the first word

Print (a.capitalize ())

The output is as follows:

Hello,Zhong Yuan Gong!!

HELLO,ZHONG YUAN GONG!!

Hello,zhong yuan gong!!

Hello,zhong yuan gong!!

String slicing

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D = '123456789'

# get the 3rd to 6th characters

Print (d [2: 6]) # what is entered here is the subscript of the string. When slicing in python, it contains the front and back, just as the output here is the substring of subscript 2-5, not the substring of subscript 2-6.

# get the last 2 characters

Print (d [- 2:])

# reverse the string

Print (d [::-1])

The output is as follows:

3456

eighty-nine

987654321

6. Delete spaces in a string

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C = 'hello world!'

# remove the spaces at the beginning and end of the string

Print (c.strip ())

# remove the space on the left side of the string

Print (c.lstrip ())

# remove the space on the right side of the string

Print (c.rstrip ())

# remove all spaces in the string

Print (c.replace (','))

The output is as follows:

Hello world!

Hello world!

Hello world!

Helloworld!!!

Note: do not confuse the strip function with the split function. The former deletes the specified characters in the string and defaults to spaces, while the latter splits the string with specified characters. The default is also spaces.

0x05: change the encoding of a string

Sometimes when we are doing file storage, there will be garbled code. At this time, we will change the code and OK it. The way is as follows

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# convert string encoding

E = 'hello,zhongyuan university, you're fine!'

Print (e.encode ('utf-8'))

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