Dictionaries in python, like HashMap in java, exist and operate in the form of key-value pairs. Its characteristics are as follows.

Access by key, not offset;

Key-value pairs are out of order;

Keys and values can be arbitrary objects;

Variable length and arbitrary nesting;

In a dictionary, there can be no sequential operation. Although dictionaries are similar to lists in some ways, don't put lists on them.

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# Encoding: utf-8

#! /usr/bin/python

# File name: map.py

Table = {'abc': 1,' def':2,' ghi':3}

print a form

# Dictionary inversion

map=dict([(v，k) for k，v in table.iteritems()])

# Dictionary traversal

For keys in map.keys ():

Print keywords, ":",mapping [keywords]

Print lens (map)

Print map.keys ()

Print map.values ()

# dictionary addition, deletion, modification and search

# It is necessary to mention here that for the expansion of dictionaries, only a new key-value pair needs to be defined.

# For lists, you can only use the append method or assign values by segments.

Map [4]="xyz "

Print map

Del map [4]

Print map

Map [3]= "Update"

Print map

if map.has_key( 1):

Print "1 key input"

{'abc': 1，' ghi': 3，' def': 2}

1 : abc

2 : def

3 : ghi

three

[ 1, 2, 3]

['abc '，' def '，' ghi']

{ 1: 'abc '，2: 'def '，3: 'ghi '，4: 'xyz'}

{ 1: 'abc '，2: 'def '，3: 'ghi'}

{ 1: 'abc '，2: 'def '，3: 'update'}

1 type