Python--15 Dictionary: When the index is not useful

The dictionary is Python's only innuendo type hash

>>> brand = [' Li ning ', ' Anta Sports ', ' Adidas ']
>>> slogan = [' Everything is possible ', ' Keep Moving ', ' impossible are nothing ']
>>> print (' Li Ning's slogan is: ', slogan[brand.index (' Plum ')])
Li Ning's slogan is: everything is possible

 Dictionary is not a sequence type, it is a mapping type

String list tuples are sequence types

Creating and accessing index symbols-- curly braces

Create dictionary mode one: key value

>>> dict1 = {' Li ning ': ' Everything is possible ', ' Anta Sports ': ' Keep Moving ', ' Adidas ': ' Impossible Is nothing '}
>>> Dict1
{' Li ning ': ' Everything is possible ', ' Anta Sports ': ' Keep Moving ', ' Adidas ': ' Impossible is nothing '}
>>> print (' Anta Sports slogan: ', dict1[' Anta Sports ')
Anta Sports slogan is: Keep Moving

>>> dict2 = {1: ' One ', 2: ' Both ', 3: ' Three '}
>>> Dict2[3]
' Three '

  Create an empty Dictionary
  >>> dict3 = {}
>>> dict3
{}
>>> dict3 = dict ()
>>> dict3
{}

Create with Dict ()

>>> help (dict)

Class Dict (Object)
| Dict (), New Empty Dictionary
| Dict (mapping), new dictionary initialized from a mapping object ' s
| (key, value) pairs
| Dict (iterable), new dictionary initialized as if via:
| D = {}
| For K, V in iterable:
| D[k] = V
| Dict (**kwargs), new dictionary initialized with the name=value pairs
| In the keyword argument list. For Example:dict (one=1, two=2)

  Dict (mapping), new dictionary initialized from a mapping object ' s
>>> dict3 = dict (' F ', ' d '), (' I ', ""), (' s ', +/-), (' H ', 104), (' C ')
Traceback (most recent):
File "<stdin>", line 1, in <module>
Typeerror:dict expect Ed at the most 1 arguments, got 5
>>> dict3 = dict ((' I ' , + +), (' s ', ' 104 '), (' H ', ' + '), (' C ', ') ')
>>> dict3
{' F ': +, ' I ': 104, ' s ': +, ' H ': $, ' C ': 67}

 (key, value) pairs

>>> dict4 = dict (code = ' Programming Changes the world ', draw = ' Every pen is a world ')
>>> Dict4
{' Code ': ' Programming changes the world ', ' draw ': ' Every pen is a world '}
>>> dict4 = dict (' Code ' = ' Programming changes the world ', draw = ' Every pen is a world ')
File "<stdin>", line 1
Syntaxerror:keyword can ' t be an expression

There is a change, no is created

>>> dict4[' code ' = ' Learning to program can change the world '
>>> dict4[' student ' = ' genius first step, but ... '
>>> Dict4
{' Code ': ' Learning to Program can change the world ', ' draw ': ' Every pen is a world ', ' student ': ' Genius first step, but ... '}

Dict () factory function (type) str (), int (), list (), tuple () ...

Fromkeys (...) re-creates a new dictionary

Dict.fromkeys (S[,v]), New dict with keys from S and values equal to V (v defaults to None)

>>> dict1 = {}

>>> Dict1.fromkeys ((+))
{1:none, 2:none, 3:none}
>>> Dict1.fromkeys ((+), ' number ')
{1: ' Number ', 2: ' Number ', 3: ' Number '}

>>> Dict1.fromkeys ((a), (' One ', ' one ', ' one ', ' three ')
{1: (' One ', ' one ', ' ' Three '), 2: (' One ', ' one ', ' three '), 3: (' One ', ' one ', ' three ')}
>>> Dict1.fromkeys ((1,3), ' number ')
{1: ' Number ', 3: ' Number '}
>>> Dict1
{}

Keys (), values (), items ()

>>> Dict1 = Dict1.fromkeys (range (32), ' likes ')
>>> Dict1
{0: ' likes ', 1: ' Likes ', 2: ' Like ', 3: ' Like ', 4: ' Like ', 5: ' Like ', 6: ' Like ', 7: ' Like ', 8: ' Like ', 9: ' Likes ', 10: ' Like ', 11: ' Like ', 12: ' Like ', 13: ' Like ', 14: ' Likes ', 15: ' Likes ', 16: ' Like ', 17: ' Like ', 18: ' Like ', 19: ' Like ', 20: ' Like ', 21: ' Like ', 22: ' Like ', 23: ' Like ', 24: ' Like ', 25: ' Like ', 26: ' Like ', 27: ' Like ', 2 8: ' Like ', 29: ' Like ', 30: ' Likes ', 31: ' Likes '}

>>> for Eachkey in Dict1.keys ():
.. print (Eachkey)
...

>>> for Eachvalue in Dict1.values ():
.. print (Eachvalue)
...

Returns a tuple

>>> for Eachitem in Dict1.items ():
.. print (Eachitem)
...

>>> Print (dict1[31])
Praise

Accessing elements that do not exist

>>> Print (dict1[32])
Traceback (most recent):
File "<stdin>", line 1, in <module>
Keyerror:32

>>> Dict1.get (+)
>>> Print (dict1.get ()) \
...
None
>>> Print (Dict1.get (32))
None
>>> Print (Dict1.get (32, ' no '))
No

 The Judgment key is in the dictionary without the member operator in the

>>> in dict1
True
>>> in dict1
False

 The sequence matches the value

 Clear () Empty the dictionary when you save user information there is a risk

>>> dict1.clear ()
>>> Dict1
{}
>>> dict1 = {}
>>> a = {' name ': ' JJ '}
>>> B = a
>>> b
{' name ': ' JJ '}
>>> a = {}
>>> a
{}
>>> b
{' name ': ' JJ '}

>>> a = b
>>> a
{' name ': ' JJ '}
>>> b
{' name ': ' JJ '}
>>> a.clear ()
>>> a
{}
>>> b
{}

Copy ()

Assignment just put a label on it, copy creates a new replication domain

>>> A = {1: ' One ', 2: ' Both ', 3: ' Three '}
>>> B = a.copy ()
>>> C = a
>>> C
{1: ' One ', 2: ' Both ', 3: ' Three '}
>>> a
{1: ' One ', 2: ' Both ', 3: ' Three '}
>>> b
{1: ' One ', 2: ' Both ', 3: ' Three '}
>>> ID (a)
139890364904936
>>> ID (b)
139890303134744
>>> ID (c)
139890364904936

 Pop () Popitem () Random bullets

>>> A.pop (2)
' Both '
>>> A.popitem ()
(3, ' three ')

 Setdefalt (Key[,value])

>>> a
{1: ' One '}
>>> a.setdefault (' small white ')
>>> a
{1: ' One ', ' Little white ': None}
>>> A.setdefault (5, ' five ')
' Five '
>>> a
{1: ' One ', ' Little white ': None, 5: ' Five '}

A.update (b) to modify a by the property of the key of B, or to modify it without adding

>>> B = {' Small white ': ' Dog '}
>>> a.update (b)
>>> a
{1: ' One ', ' Little white ': ' Dog ', 5: ' Five '}

>>> B = {' Small yellow ': ' da Dog '}
>>> a.update (b)
>>> a
{1: ' One ', ' Little white ': ' Dog ', 5: ' Five ', ' Little Yellow ': ' Da Dog '}

Python--15 Dictionary: When the index is not useful