Python sequence and Python Sequence

Python sequence and Python Sequence
Python contains six built-in sequences: List, tuples, strings, Unicode, buffer objects, and xrange objects.

Common sequence operations include indexing, sharding, adding, multiplication, and membership.

There are also built-in functions such as length (len), minimum value (min), and maximum value (mix ).

• List

Basic list operations

# Create a list> nums = [1, 2, 3, 5]> nums [1, 2, 3, 5] # element assignment >>> nums [2] = 7 >>> nums [1, 2, 7, 5] >>># Delete element >>> del nums [0] >>> nums [2, 7, 5] # list function (type) you can create a list based on the string >>> st = list ('hello') >>> st ['h', 'E', 'l', 'l ', 'o'] # using indexes to access a single element, Using fragments to access a certain range of elements >>> nums = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] >>> nums [] [3, 4, 5, 6] ## to enable a shard to include the last element of the list, you must provide an index greater than the last element index as the boundary> nums [] [3, 4, 5, 6, 7, 8, 9, 10] ## count from the end> nums [-3:] [8, 9, 10] # count from the Start> nums [: 3] [1, 2, 3] # entire list> nums [:] [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] # step size> nums [] [1, 4, 7, 10]> nums [: 4] [1, 5, 9] >>> nums [:-2] [10, 8, 6, 4, 2] ## partition assignment >>> name = list ('hemin') >>> name ['h', 'E', 'M', 'I ', 'N'] >>>> name [2:] = list ('shen') >>> name ['h', 'E', 's', 'h ', 'E', 'n'] # insert and delete> nums2 = []> nums2 [] = [2, 3, 4] >>> nums2 [1, 2, 3, 4, 5] >>> nums2 [] = [] >>> nums2 [1, 5]

List Method

# Append () append: directly modifies the original list, instead of returning the Modified list >>> letters = ['A', 'B ', "c"] >>> letters. append ('D') >>> letters ['A', 'B', 'C', 'D'] # count () count the number of occurrences of a specified element, letters = list ('abcdeeefggggh') >>> letters. count ('G') 4 # append multiple values to the end of the extend () list, alternatively, you can use the new list to expand the original list >>> letters2 = list ('ijklmn ') >>> letters. extend (letters2) >>> letters ['A', 'A', 'B', 'C', 'D', 'E', 'E ', 'E', 'F', 'G', 'h', 'I', 'J', 'k ', 'l', 'M', 'n'] # Note: Extend and append directly modify the original list, and the connection operation returns a new list, which is less efficient than the extend method >>> a = [1, 2, 3] >>> B = [, 6] >>> a + B [1, 2, 3, 4, 5, 6] >>> a [1, 2, 3] # a not changed # insert () insert> nums = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] >>> nums. insert (2, 'two') >>> nums [1, 2, 'two', 3, 4, 5, 6, 7, 8, 9, 10] # The pop method removes an element from the List (removed based on the index) >>> nums. pop () # remove the last element 10 by default> nums [1, 2, 'two', 3, 4, 5, 6, 7, 8, 9] >>> nums. pop (3) 3 >>> nums [1, 2, 'two', 4, 5, 6, The 7, 8, 9] # remove () remove method removes the first matching item of an element in the list (based on the element) >>> letters = list ('abccd ') >>> letters. remove ('C') >>> letters ['A', 'B', 'C', 'D'] # reverse () list element reverse storage> le = list ('abc')> le. reverse () >>> le ['C', 'B', 'a'] >>># list copy >>> x = [5, 4, 7] >>> y = x # in this way, x and y point to the same list >>> z = x [:] # copy it like this >>> x. sort () >>> y [4, 5, 7] >>> z [5, 4, 7] # sort () list sorting> num = [,]> num. sort ()> num [1, 2, 5, 6, 7, 9] # sor T (*, key = None, reverse = None), key indicates the sort keyword, and reserve indicates whether to reverse the order. The sort of Python3 is in stable sorting. >>> A = ['abc', 'abcd', 'AB']>. sort (key = len) >>> a ['AB', 'abc', 'abcd'] # clear () clear list # copy () copy list

• Tuples

# Tuples cannot be modified # create tuples >>> 1, 2, 3 (1, 2, 3) >>> 'A', 'B', 'C' ('A ', 'B', 'C') >>>> () # null tuples () >>>> ('D',) # contain only one element ('D ',) # significance of tuples: tuples can be used as keys in ing, but the list does not work. tuples exist as methods and return values of many built-in functions.