Python中数组用法大全

#!/usr/bin/env python #

[SNIPPET_NAME: Lists 101]

[SNIPPET_CATEGORIES: Python Core]

[SNIPPET_DESCRIPTION: Basic and not so basic list operations]

[SNIPPET_AUTHOR: Bruno Girin <brunogirin@gmail.com>]

[SNIPPET_LICENSE: GPL]

This snippet demonstrates how the basics on lists: how to create, add,

remove items, get items or slices, sort, etc.

#

First, let's create simple list

# print "Create a simple list" simpleList = ["Karmic", "Lucid", "Hardy", "Jaunty", "Intrepid"]

print it

print simpleList #

Interrogate the list

# print "\nInterrogate the list"

get item 3: lists start counting at 0 so it should be Jaunty

print simpleList[3]

we can also get a slice

print simpleList[2:4]

get the first three items

print simpleList[:3]

or all items from number index 3 (which is the fourth item) to the end

print simpleList[3:]

we can also take every other item, as a slice is defined

like this: start:stop:step

print simpleList[::2]

get the length of the list

print len(simpleList)

we can get the index of an item in the list

print simpleList.index("Hardy")

and when the list doesn't contain the item, we get an error that we can catch

try: print simpleList.index("Feisty") except ValueError: print "The list doesn't contain the item Feisty" #

Modify the list

# print "\nModify the list"

add another item

simpleList.append("Twisty") print simpleList

oops! let's sort this out by replacing in place

simpleList[5] = "Gutsy" print simpleList

extend the list with another one

otherList = ["Edgy", "Breezy"] simpleList.extend(otherList) print simpleList

remove an item from the list (Hardy should not be in the list anymore)

del simpleList[2] print simpleList

insert an item in the middle of the list

simpleList.insert(4, "Hardy") print simpleList

remove an item by its value rather than its index

simpleList.remove("Edgy") print simpleList #

Create modified copies of the list

# print "\nCreate modified copies of the list"

sort it

print sorted(simpleList)

join it to produce a custom print

print ' => '.join(sorted(simpleList))

lists can contain the same item several times so if we add Lucid again:

simpleList.append("Lucid")

we have it twice in the list (easier to see if we sort it)

print sorted(simpleList)

but we can get round that by transforming it into a set, which is a list

with no duplicates; and of course we can also sort the set

print sorted(set(simpleList)) #

Iterate over the list

# print "\nIterate over the list" for i in simpleList: print i.upper()

but if we want to create another list by applying the same expression to

each item, we can use a list comprehension

upList = [i.upper() for i in sorted(set(simpleList))] print upList </pre>