如下代码是关于python中的字典用法大全的代码。

#!/usr/bin/env python## [SNIPPET_NAME: Dictionaries 101]# [SNIPPET_CATEGORIES: Python Core]# [SNIPPET_DESCRIPTION: Basic and not so basic dictionary operations]# [SNIPPET_AUTHOR: Bruno Girin <brunogirin@gmail.com>]# [SNIPPET_LICENSE: GPL]# This snippet demonstrates how the basics on dictionaries: how to create, add,# remove items, get items, iterate, etc.## First, let's create simple dictionary. A dictionary (called map in Java hash# in perl) is similar to a list with the difference that the key doesn't# have to be an integer, it can be anything.## A dictionary is enclosed in curly brackets and each key is mapped to its# corresponding value with a colon. So in the dictionary below, we associate# the key Karmic with the value 9.10 and so on for the 5 pairs.#print "Create a simple dictionary"simpleDict = {"Karmic": "9.10", "Lucid": "10.04", "Hardy": "7.10", "Jaunty": "8.10", "Intrepid": "8.04"}# print itprint simpleDict## Another way to create a dictionary is to zip two lists containing the keys# and values in the same order to create a list of tuples, which we can then# pass to the dict() method to create a dictionary.#myKeys = ['Feisty', 'Edgy', 'Dapper']myValues = ['7.04', '6.10', '6.06']otherDict = dict(zip(myKeys, myValues))print otherDict## Interrogate the dictionary. It works exactly the same as with a list, with the# exception that the key is no longer an integer.#print "nInterrogate the dictionary"# get for value for key Jauntyprint simpleDict['Jaunty']# get the length of the dictionaryprint len(simpleDict)# check if the dictionary contains the key Lucidprint 'Lucid' in simpleDictprint 'Breezy' in simpleDict## Modify the dictionary#print "nModify the dictionary"# add another itemsimpleDict['Hoary'] = '5.06'print simpleDict# oops! let's sort this out by replacing in placesimpleDict['Hoary'] = '5.04'print simpleDict# update the dictionary with mappings from another onesimpleDict.update(otherDict)print simpleDict# remove an item from the list (Hardy should not be in the list anymore)del simpleDict['Hoary']print simpleDict## Iterate over the dictionary. A dictionary doesn't enforce a natural ordering# like a list but we can still iterate over it in multiple ways.# However, note that when you iterate, the order in which the items are# retrieved is unspecified.#print "nIterate over the dictionary"print "nby keys"for k in simpleDict.keys(): print kprint "nby values"for v in simpleDict.values(): print vprint "nby items"# note the syntax to retrieve the key and value at the same timefor k, v in simpleDict.items(): print k, '=>', v## More interesting transformations from list to dictionary and vice versa.# List comprehension allow you to do a lot of interesting stuff, in particular# tranforming lists into dictionaries and the other way around.#print "nList to dictionary and vice versa"# First, let's transform our dictinary into a list of tuplessimpleList = [(k, v) for k, v in simpleDict.items() ]print simpleList# Create a map from a list with the list's entry as key and the index as value# This method takes advantage of another way of creating a map, using a# sequence of tuples, so in practice, we create a tuple for each item in the# list, create a list from all the tuples using a list comprehension and pass# it as argument to the dict() functioncityList = ['London', 'Paris', 'New York', 'Tokyo']cityDict = dict([(x, i) for i, x in enumerate(cityList)])print cityDict# Create a map from a number to its squareprint squareDict