//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]