---

字典实例：建立学生学号成绩字典，做增删改查遍历操作。

================ RESTART: C:/Users/Administrator/Desktop/1.py ================

>>> d={'hello':88,'insert':12,'input':45,'open':56}

>>> d['open']

56

>>> d.pop('insert')

12

>>> d.keys()

dict_keys(['hello', 'input', 'open'])

>>> d.values()

dict_values([88, 45, 56])

>>> d.items()

dict_items([('hello', 88), ('input', 45), ('open', 56)])

>>> d.get('hi',' ')

' '

>>> d.get('jis','nius')

'nius'

>>> d.get('open',' ')

56

>>> del(d['hello'])

>>> d

{'input': 45, 'open': 56}

>>> for i in d:

print(i,d[i])

input 45

open 56

>>>

列表，元组，字典，集合的遍历。

总结列表，元组，字典，集合的联系与区别。

列表：list是一种有序的序列，正向递增、反向递减序号；可以随时添加和删除其中的元素；没有长度限制，元素类型可以不同。

元组：tuple和list非常类似；都是内置的集合；tuple一旦初始化就不能修改。

字典：是用空间来换取时间的一种方法。

和list比较；特点是：查找和插入的速度极快，不会随着key的增加而变慢，需要占用大量的内存，内存浪费多。

和list相反；查找和插入的时间随着元素的增加而增加；占用空间小，浪费内存很少。

集合：也是一组key的集合，但是不存储values；没有重复的key；创建一个set，需要提供一个list做为输入集合；set 是无序的。

英文词频统计实例

Python 3.6.2 (v3.6.2:5fd33b5, Jul 8 2017, 04:57:36) [MSC v.1900 64 bit (AMD64)] on win32

Type "copyright", "credits" or "license()" for more information.

>>> sing='''Hello, it's me

I was wondering if after all these years you'd like to meet

To go over everything

They say that time's supposed to heal ya

But I ain't done much healing

Hello, can you hear me?

I'm in California dreaming about who we used to be

When we were younger and free

I've forgotten how it felt

Before the world fell at our feet

There's such a difference between us

And a million miles

Hello from the other side

I must have called a thousand times

To tell you I'm sorry for everything that I've done

But when I call, you never seem to be home

Hello from the outside

At least I can say that I've tried

To tell you I'm sorry for breaking your heart

But it don't matter, it clearly doesn't tear you apart

Anymore

Hello, how are you?

It's so typical of me to talk about myself, I'm sorry

I hope that you're well

Did you ever make it out of that town

Where nothing ever happened?

It's no secret that the both of us

Are running out of time

So hello from the other side (other side)

I must have called a thousand times (thousand times)

To tell you I'm sorry for everything that I've done

But when I call, you never seem to be home

Hello from the outside (outside)

At least I can say that I've tried (I've tried)

To tell you I'm sorry for breaking your heart

But it don't matter, it clearly doesn't tear you apart

Anymore

Ooh, anymore

Ooh, anymore

Ooh, anymore

Anymore

So hello from the other side (other side)

I must have called a thousand times (thousand times)

To tell you I'm sorry for everything that I've done

But when I call, you never seem to be home

Hello from the outside (outside)

At least I can say that I've tried (I've tried)

To tell you I'm sorry for breaking your heart

But it don't matter, it clearly doesn't tear you apart

Anymore'''

>>> s=sing.lower()

>>> for i in ',.?/!':

s=sing.replace(i,' ')

>>> s=sing.split(' ')

>>> words=set(s)

>>> d={}

>>> d['we']=s.count('we')

>>> for i in words:

d[i]=s.count(i)

>>> for i in d:

print('{0:<10}{1}'.format(i,d[i]))

we 2

used 1

sorry 6

I've 6

must 3

times

To 1

tried

To 1

miles

Hello1

hello 2

ain't 1

to 7

outside

At1

go 1

(other 2

thousand 3

least 3

talk 1

supposed 1

I 7

that 10

dreaming 1

so 1

apart

Anymore1

sorry

I 1

when 3

you're 1

feet

There's1

meet

To 1

clearly 3

us

And 1

was 1

like 1

much 1

it 8

(thousand 2

called 3

home

Hello3

times)

To 2

tried 2

times 2

everything

They1

time

So 1

younger 1

our 1

side)

I 2

us

Are 1

you'd 1

free

I've 1

who 1

I'm 7

both 1

never 3

these 1

forgotten 1

me

I 1

heal 1

all 1

wondering 1

world 1

everything3

running 1

(outside)

At2

you?

It's 1

side

I 1

don't 3

(I've 2

apart

Anymore

Hello,1

secret 1

years 1

between 1

the 8

Hello, 1

me?

I'm 1

after 1

for 6

side 2

myself, 1

were 1

California1

doesn't 3

done 1

can 4

ever 2

typical 1

out 2

such 1

anymore

Anymore

So1

outside 2

over 1

heart

But 3

difference1

million 1

a 5

breaking 3

are 1

done

But 3

of 4

well

Did 1

healing

Hello,1

other 3

it's 1

at 1

ya

But 1

tell 6

hear 1

call, 3

town

Where1

say 4

from 6

fell 1

nothing 1

and 1

felt

Before1

be 3

have 3

about 2

hope 1

no 1

tried)

To 2

your 3

make 1

seem 3

anymore

Ooh,2

be

When 1

me 1

how 2

you 14

in 1

apart

Anymore

Ooh,1

if 1

matter, 3

time's 1

happened?

It's1

tear 3

>>>