Python Jobs (data type Cont.)

Data type (cont.)

1 List

Definition: [] separated by commas, by index, storing various data types, each position represents an element

Characteristics

1 can hold multiple values

2 can modify the corresponding value of the index position, variable

3 list elements are defined in left-to-right order, subscript is accessed sequentially from 0, ordered

1 list_test[' LHF, ' k, ' OK ']2 or 3 list-test=list (' abc ') 4 or 5 list_test=list ([' LHF ', ' + ', ' OK '])

List common actions

Index

Slice

Additional

Delete

Length

Slice

Cycle

Contains

2 tuples

Definition: Similar to a list, except [] Change to ()

Features: 1 can hold a value of 2 immutable 3 The tuple element is defined in the order from sitting to right, the subscript is accessed sequentially from 0, ordered

Tuple creation

1 age= (11,22,33,44,55) 2 or 3 ages=tuple ((11,22,33,44,55))

Tuples Common operations

Index

Slice

Cycle

Length

Contains

3 Dictionaries

Definition: (key:value1,key2:value2), key-value structure, key must be hash

Attribute 1 can hold multiple values 2 can modify the value corresponding to the specified key, can be changed to 3 unordered

Dictionary creation

person={' name ': ' SB ', ' Age ': 18} or Person=dict (name= ' SB ', age=18) person=dict (name= ' SB ', age=18) person=dict ([' Name ', ' SB '],[' age ',] {}.fromkeys (seq,100) #不指定100 default to None Note "Dic={}.fromkeys ([' K1 ', ' K2 '],[])" dic{' K1 ': [1], ' K2 ': [1] }

Dictionary common Operations

Index

New

Delete

Key, value, key-value pairs

Length

4 Collection

Definition: A collection of different elements, a set of unordered permutations of hasha values that can be used as a dictionary key

Characteristics:

1 The purpose of the collection is to store different values together between different sets for relational operations, without having to tangle the individual values in the set

Creation of collections

{1,2,3,1}

Or

Define a mutable collection set

>>>set_test=set (' Hello ')

>>>set_test

Frozenset ({' 1 ', ' 2 ', ' h ', ' O '})

Collection common operations: relational operations

Inch

Not in

==

!=

<,<=

>,>=

|,|=: The collection

&.&=: Intersection

-,-=: Difference Set

^,^=: Symmetric difference Set

Python Jobs (data type Cont.)