Python Base Three

//sixth day to study python(2016/8/7)

32. In python , there are have an special type dictionary , it is same with oc.

such as:

dicOne = {'wyg':'write code change world', 'roy':'you cand do it', 'tom':'just do it'}

dicOne

->

{'wyg':'write code change world', 'roy':'you cand do it', 'tom':'just do it'}

dicOne['wyg']

->

'wirte code change world'

dicOne['wyg'] = 'believe youself'

dicOne

->

{'wyg':'believe youself', 'roy':'you cand do it', 'tom':'just do it'}

dicTwo = dict(wyg = 'just do it', roy = 'you can do it')

dicTwo

->

{'wyg':'just do it', 'roy':'you can do it'}

dicThree = dict((('r':'rrr'),('t':'ttt')))

dicThree

->

{'r':'rrr','t':'ttt'}

33. In python ,dictionary type we can use everywhere, so we should learn it more deeply.

fromkeys()

dict1 = {}

dict1.fromkeys((1, 2, 3))

->

{1:None, 2:None, 3:None}

dict1.fromkeys((1,2,3),'Number')

->

{1:'Number', 2:'Number', 3:'Number'}

dict1.fromkeys((1,2,3),('one','two','three'))

->

{1: ('one', 'two', 'three'), 2: ('one', 'two', 'three'), 3: ('one', 'two', 'three')}

keys()

dict1 = dict.fromkey(range(5),'roy')

dict1

->

{0:'roy',1:'roy',2:'roy',3:'roy',4:'roy'}

for eachKey in dict1.keys():

print(eachKey)

->

0

1

2

3

4

5

values()

for eachValue dict1.values():

print(eachValue)

->

roy

roy

roy

roy

roy

items()

for eachItem in dict1.items():

print(eachItem)

->

(0, 'roy')
      (1, 'roy')
      (2, 'roy')
      (3, 'roy')
      (4, 'roy')

get()
      dict1.get(0)

->

'roy'

print(dict1.get(100))

->

None

dict1.get(1,'no keyvalue')

->

'roy'

dict1.get(100,'no keyvalue')

->

'no keyvalue'

in , not in (key)

3 in dict1

True

100 in dict1

False

clear()

dict1.clear()

->

{}
      copy() (light copy)

a = {1:'one',2:'two'}

b = a.copy()

c = a

id(a)    id(b)   id(c)

->

4346314824     4386886856     4346314824

c[3] = 'three'

a

->

{1:'one',2:'two',3:'three'}

b

->

{1:'one',2:'two'}

c

->

{1:'one',2:'two',3:'three'}

pop()
    a.pop(2)

->

{1:'one',2:'three'}

popitem()

a.popitem()

-> rand pop an object

setdefault()

a = {1:'one'}

a.setdefault(2)

a

->

{1:'one',2:None}

a.setdefault(3,'three')

{1:'one',2:None,3:'three}

update()
    b = {'roy':'wyg'}

a.update(b)

->

{1:'one',2:None,3:'three,'roy':'wyg'}

34. we have learned dictionary ,now we learn set continue.

num = {}

type(num)

<class 'dict' at 0x100229b60>

num = {1,2,3}

type(num)

<class 'set' at 0x10022e420>

in set ,all value is only but no support index. such as:

num2 = {1,2,3,4,5,5,6}

num2

->

{1,2,3,4,5,6}

num3 = set([1,2,3,4])

num3

->

{1,2,3,4}

now how can remove repeat value from list

such as:

a = [1,2,3,4,5,5,6]

b = []

for each in a:

if each not in b:

b.append(each)

b

->

[1,2,3,4,5,6]

now that we have learned set ,how to achieve it by set

a = list(set(a))

->

[1,2,3,4,5,6]