Python learns the sequence of data types, and python Data Types

Python learns the sequence of data types, and python Data Types

I. Sequence (this article uses python3.5)
######################################## ####################
# List and tuples are all Sequences
# Features:
#1. You can obtain specific elements through indexes.
#2. You can obtain a small sequence through the slice operation.
# Basic operations
Str = "abc ";
Str1 = "efg ";
Print (len (str); # obtain the sequence length
Print (str + str1); # concatenate Sequences
Print (str * 5); # repeat the sequence for five times abcabcabcabcabc
Print ('A' in str); # determine whether an element exists in the sequence
Print (max (str); # obtain the largest element in the sequence
Print (min (str); # obtain the smallest element in the sequence
# The cmp (x, y) function is used to compare two objects. If x <y returns-1, if x = y, 0 is returned. If x> y, 1 is returned. This function is canceled in python3.
Ii. String Sequence

# String is a sequence type data each character has its own bucket string cannot be changed str4 = "abcdefgh"; print (str4 [0]); # a obtain print (str4 [1] + str4 [2]) through the index; # bcstr5 = str4 []; # print (str5) is not included after the first entry ); # bcdeprint (str4 [: 4]); # abcd intercepts 0-4 strings (excluding [4]) print (str4 [4:]); # efg intercepts all characters from subscript 4 to the End of print (str4 [: 1]); # each step is set to abcdefuplint (str4 [: 2]); # aceg # negative subscript print (str4 [-1]); # hprint (str4 [-4:-1]); # efg does not include str4 [-1]

3. tuple)

Feature: the Python tuples are similar to the list. The difference is that the elements of the tuples cannot be modified, and the tuples use parentheses.

######################################## ############################## ################ Features of tuples: the value of the tuples cannot be changed. The tuples have all the operations in sequence # the declaration of the tuples arr = (); # The empty tuples arr1 = (2 ,); # single element in the tuples # operation arr2 = name, age, gender = ("Zhang San", 20, "male"); print (name); # Zhang San

Iv. List)

A list is a data structure that processes a group of Ordered items. A list is a variable type of data that has all the operations of a sequence.

# The list is the data structure that processes a group of Ordered items, and the list is a variable type of data with all the operations of the sequence # list declaration list = []; # Empty list list1 = [1, 2, 3]; list2 = ["", 10]; # assign a value to the list element (modify the value) print (list2 [3]); list2 [3] = 50; print (list2 [3]); # add data list2.append ("zhangsi") to the list "); # Add print (list2) after list2; # ['zhangzhang ', 'zhang2', 'zhangsan', 50, 20, 10, 'zhang si'] list2.remove (list2 [6]); # The print (list2) elements of the list are deleted; # ['zhang zhang', 'zhang 2', 'zhang san ', 50, 20, 10] del (list2 [5]); # Delete the specified Element print (list2) in the list; # ['zhang zhang', 'zhang 2', 'zhang san ', 50, 20]

V. Dictionary (dict)

# Dictionary ing type hash table dictionary objects can be changed. Key values must use immutable objects. Key value types can be different.

# Dictionary ing type hash table dictionary object is variable, key value must use an immutable object, key value type can be different # method: # keys () Return key class table values () return Value List # items () returns the tuples containing key-value pairs # create map of the dictionary ={}; # empty dictionary map1 = {'name': "Lee ", 'age': "12"}; map2 = {'name': "Zhang San", 'age': "23", 'tel ': 12345678901 }; # obtain the corresponding valueprint (map2 ['name']) based on the key; # Zhang San print ("get =" + map2.get ("name ")); print ("getNull =" + map2.get ("name_1", 'null'); # return null if the Name does not exist # traverse the self-dictionary for k in map2: print (k ); # key value print (map2 [k]); # values value # Add Value map2 ["addrss"] = "Beijing"; print (map2 ["addrss"]); # Beijing # modify the value map2 ["tel"] = 13456727890123; print (map2 ["tel"]); # Delete del (map2 ["tel"]); # Delete the specified Element map2.pop ("name"); # Remove the specified Element and return the value of this element map2.clear (); # Clear the dictionary # destroy the entire dictionary del (map2 ); # Use the factory production dictionary dict ()