组合数据类型练习，英文词频统计实例上

1、字典

d={'Tom':'01','Helen':'02','David':'03','Jim':'04'}
增
d['Wang']='05'
删
d.pop('Tom')
改
d['Tom']='06'
查
d['Tom']

2、集合

a=set('12345')
b=set('56789')
增
a.add('6')
删
b.remove('9')
并集
a&b
交集
a|b
a-b

　　3、英文词频统计实例

abc='''every night in my dreams
i see you, i feel you,
that is how i know you go on
far across the distance
and spaces between us
you have come to show you go on
near, far, wherever you are
i believe that the heart does go on
once more you open the door
and you're here in my heart
and my heart will go on and on
love can touch us one time
and last for a lifetime
and never let go till we're one
love was when i loved you
one true time i hold to
in my life we'll always go on
near, far, wherever you are
i believe that the heart does go on
once more you open the door
and you're here in my heart
and my heart will go on and on
there is some love that will not go away
you're here, there's nothing i fear,
and i know that my heart will go on
we'll stay forever this way
you are safe in my heart
AND my heart will go on and on'''

abc=abc.lower()
for i in ',.':
    abc=abc.replace(i,' ')
words=abc.split(' ')
print(words)
di{}
words.sort()
disc = set(words)
for i in disc:
     di[i] = 0
for i in words:
    di[i] = di[i]+1
items = di.items()
print(items)<br data-filtered="filtered"><br data-filtered="filtered"><br data-filtered="filtered">

　　

　　

 3、总结列表，元组，字典，集合的联系与区别

   列表查找和插入的时间随元素的增加而增加，占用空间小，浪费内存很少；列表可以有N个元素，元素的类型是任意的，与列表本身无关。字典的查找和插入速度极快，不会随key的增加而变慢，需要占用大量内存，内存浪费多。字典使用键—值存储名具有极快的查找速度。字典的key必须是不可变对象。Python的集合(set)和其他语言类似, 是一个无序不重复元素集, 基本功能包括关系测试和消除重复元素. 集合对象还支持union(联合), intersection(交), difference(差)和sysmmetric difference(对称差集)等数学运算.由于集合是无序的,所以，sets 不支持 索引, 分片, 或其它类序列（sequence-like）的操作。

4、列表，元组，字典，集合的遍历

列表
l = list('23132111123132')
元组
t = tuple('1233211232123')
字典
d = dict(zip([1,2,3,4],[4,3,2,1]))
集合
s = set(l)
for i in l:
print(i)
for i in t:
print(i)
for i in s:
print(i)
for i in d:
print(i)