Python学习2

python中有三种内部数据结构：列表、元组、字典（using_list.py，using_tuple.py， using——dict.py）
list：列表。shoplist = ['apple', 'mango', 'carrot', 'banana']
方法，尾部添加shoplist.append('rice')，排序shoplist.sort()，删除del shoplist[i]

# Filename: using_list.py
# This is my shopping list
shoplist = ['apple', 'mango', 'carrot', 'banana']
print 'i have', len(shoplist), 'items to choose'
print 'these items are:',
for item in shoplist:
    print item,
print '\nI also have to buy rice'
shoplist.append('rice')
print 'my shoplist now is', shoplist
print 'i will sort my list now'
shoplist.sort()
print 'Sorted shopping list is', shoplist
print 'The first item i will buy is', shoplist[0]
olditem = shoplist[0]
del shoplist[0]
print 'i bought the', olditem
print 'My shopping list is now', shoplist 

测试结果：
i have 4 items to choose
these items are: apple mango carrot banana 
I also have to buy rice
my shoplist now is ['apple', 'mango', 'carrot', 'banana', 'rice']
i will sort my list now
Sorted shopping list is ['apple', 'banana', 'carrot', 'mango', 'rice']
The first item i will buy is apple
i bought the apple
My shopping list is now ['banana', 'carrot', 'mango', 'rice']

 

tuple：元组。与列表类似，只是不能被修改。
zoo = ('wolf', 'elephant', 'penguin') new_zoo = ('monkey', 'dolphin', zoo)

元组在打印语句中应用：name = 'Mike' age = 22 print '%s is years old ' %(name, age)

# Filename: using_tuple.py
zoo = ('wolf', 'elephant', 'penguin')
print 'number of animals in the zoo is', len(zoo)
new_zoo = ('monkey', 'dolphin', zoo)
print 'number of animals in the new zoo is', len(new_zoo)
print 'all animals in the new zoo are', new_zoo
print 'Animals brought from old zoo are', new_zoo[2]
print 'last animal brought from old zoo is', new_zoo[2][2]

测试结果：
number of animals in the zoo is 3
number of animals in the new zoo is 3
all animals in the new zoo are ('monkey', 'dolphin', ('wolf', 'elephant', 'penguin'))
Animals brought from old zoo are ('wolf', 'elephant', 'penguin')
last animal brought from old zoo is penguin

 

dict:字典。由键值对构成，键不可改变，值可修改。 d = {key1 : value1, key2 : value2}
方法：ab.items()，ab.has_key('Guido')，删除del
items()方法返回一个元组的列表

# Filename: using_dict.py
ab = {'Swaroop' : 'swaroopch@byteofpython.info',
        'Larry' : 'larry@wall.org',
        'Matsumoto' : 'matz@ruby-lang.org',
        'Spammer' : 'spammer@hotmail.com'}
print "Swaroop's address is %s" %ab['Swaroop']

# Adding a key/value pair
ab['Guido'] = 'guido@python.org'
print '\nThere are %d contacts in the address-book\n' %len(ab)
for name, address in ab.items():
    print 'Contact %s at %s' %(name, address)
if 'Guido' in ab: # ab.has_key('Guido')
    print "\nGuido's address is %s" %ab['Guido']

测试结果：
Swaroop's address is swaroopch@byteofpython.info

There are 5 contacts in the address-book

Contact Swaroop at swaroopch@byteofpython.info
Contact Matsumoto at matz@ruby-lang.org
Contact Larry at larry@wall.org
Contact Spammer at spammer@hotmail.com
Contact Guido at guido@python.org

Guido's address is guido@python.org

 

序列（seq.py）
元组、列表都是序列。共性：索引操作符、切片操作符
索引可以是负数，此时从尾端开始计数。
切片开始位置在序列切片位置中，结束位置被排除在外

# FIlename: seq.py
shoplist = ['apple', 'mango', 'carrot', 'banana']
# Indexing or Subscriprion operation
print 'Item 0 is', shoplist[0]
print 'Item 1 is', shoplist[1]
print 'Item 2 is', shoplist[2]
print 'Item 3 is', shoplist[3]
print 'Item -1 is', shoplist[-1]
print 'Item -2 is', shoplist[-2]

# slicing on a list
print 'Item 1 to 3 is', shoplist[1:3]
print 'Item 2 to end is', shoplist[2:]
print 'Item 1 to -1 is', shoplist[1:-1]
print 'Item start to end is', shoplist[:]

# slicing on a string
name = 'swaroop'
print 'characters 1 to 3 is', name[1:3]
print 'characters 2 to end is', name[2:]
print 'characters 1 to -1 is', name[1:-1]
print 'characters start to end is', name[:]

测试结果：
Item 0 is apple
Item 1 is mango
Item 2 is carrot
Item 3 is banana
Item -1 is banana
Item -2 is carrot
Item 1 to 3 is ['mango', 'carrot']
Item 2 to end is ['carrot', 'banana']
Item 1 to -1 is ['mango', 'carrot']
Item start to end is ['apple', 'mango', 'carrot', 'banana']
characters 1 to 3 is wa
characters 2 to end is aroop
characters 1 to -1 is waroo
characters start to end is swaroop

 

参考（类似c#引用）（reference.py）
mylist = shoplist, 引用
mylist = shoplist[:]， 完全复制

# Filename: reference.py
print 'Simple Assignment'
shoplist = ['apple', 'mango', 'carrot', 'banana']
# mylist is just another name pointed to the same object!
mylist = shoplist
del shoplist[0]
print 'shoplist is', shoplist
print 'mylist is', mylist
# make a copy by doing a full slice
mylist = shoplist[:]
del mylist[0]
print 'shoplist is', shoplist
print 'mylst is', mylist

测试结果：
Simple Assignment
shoplist is ['mango', 'carrot', 'banana']
mylist is ['mango', 'carrot', 'banana']
shoplist is ['mango', 'carrot', 'banana']
mylst is ['carrot', 'banana']

 

字符串str类的方法（str_methods.py）
startwith():测试字符串是否以指定字符串开始
in：测试字符串是否含有指定字符串
find():返回指定字符串在字符串中的位置，没有则返回-1
join():可作为序列的连接字符串

# Filename: str_methods.py
name = 'Swaroop'
if name.startswith('Swa'):
    print 'Yes, the string strats with "Swa"'
if 'a' in name:
    print 'Yes, it contains the string "a"'
if name.find('war') != -1:
    print 'Yes, it contains the string "war"'
delimiter = '_*_'
mylist = ['Brazil', 'Russia', 'India', 'China']
print delimiter.join(mylist)

测试结果：
Yes, the string strats with "Swa"
Yes, it contains the string "a"
Yes, it contains the string "war"
Brazil_*_Russia_*_India_*_China