Several methods of dictionary in python

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>>> phonebook={'Alice':'2897','Alan':'0987','Jery':'6754'}

Dict functions

>>> items=[('name','Gumby'),('age',42)]>>> d=dict(items)>>> d{'age': 42, 'name': 'Gumby'}>>> d['name']'Gumby'>>> d=dict(name='July',age=24)>>> d{'age': 24, 'name': 'July'}

Basic dictionary operations (mostly similar to sequences)

Len (d) returns the number of key-value pairs in d.

D [k] returns the value associated with the key k.

D [k] = v associate value v to k

Del d [k] delete key k

K in d check whether d contains the key k

Format a string

>>> phonebook{'Jery': '6754', 'Alice': '2897', 'Alan': '0987'}>>> "Alan's phone number is %(Alan)s." % phonebook"Alan's phone number is 0987."

Method:

Clear all items in the dictionary

>>> D ={}>> d ['name'] = 'Gumby' >>> d ['age'] = 42 >>>> d {'age ': 42, 'name': 'Gumby'} >>> d. clear () >>> d {}>>> x ={}>> y = x # x and y correspond to the same dictionary >>> x ['key'] = 'value' >>> y {'key ': 'value' >>>> x ={}# x is associated with the new empty dictionary >>> y {'key ': 'value' >>>> x ={}>> y = x >>>> x ['key'] = 'value' >>>> y {'key ': 'value' }>>> x. clear () >>> y {}

Copy returns a new dictionary with the same key-value pairs)

>>> X = {'name': 'admin', 'machines ': ['foo', 'bar', 'bax'] >>> y = x. copy () >>> y ['name'] = 'yhk '# replace the value. The original dictionary is not affected >>> y ['machines']. remove ('bar') # Modify a value (the original dictionary is changed)> y {'name': 'yhk ', 'machines ': ['foo', 'bax '] >>> x {'name': 'admin', 'machines': ['foo', 'bax ']}

Deep copy

>>> from copy import deepcopy>>> d={}>>> d['name']=['Aly','Bob']>>> c=d.copy()>>> e=deepcopy(d)>>> d['name'].append('Ageal')>>> c{'name': ['Aly', 'Bob', 'Ageal']}>>> e{'name': ['Aly', 'Bob']}

Fromkeys creates a new dictionary using the given key. the default value of each key is none.

>>> {}.fromkeys(['name','age']){'age': None, 'name': None}>>> dict.fromkeys(['name','age']){'age': None, 'name': None}>>> dict.fromkeys(['name','age'],'(unknown)'){'age': '(unknown)', 'name': '(unknown)'}

Get

>>> d={}>>> print d['name']Traceback (most recent call last):  File "
 
  ", line 1, in 
  
       print d['name']KeyError: 'name'>>> print d.get('name')None>>> d.get('name','N/A')'N/A'>>> d['name']='Eric'>>> d.get('name')'Eric'
  
 

Has_key: Check whether the dictionary has a given key (python3.0 does not have this function)

>>> d={}>>> d.has_key('name')False>>> d['name']='Eric'>>> d.has_key('name')True

Items and iteritems

Items returns all Dictionary items in the list. Each of these list items comes from (key, value)

Iteritems returns an iterator object

>>> d={'title':'My Time!','url':'http://www,python.org','spam':0}>>> d.items()[('url', 'http://www,python.org'), ('spam', 0), ('title', 'My Time!')]>>> s=d.iteritems()>>> s
 
  >>> list(s)[('url', 'http://www,python.org'), ('spam', 0), ('title', 'My Time!')]
 

Keys and iterkeys keys return the keys in the dictionary to iterkeys in the form of a list and return the iterator for the keys

Pop removal

>>> d={'x':1,'y':2}>>> d.pop('x')>>> d{'y': 2}

Popitem remove random items

>>> d={'x':1,'y':2}>>> d.popitem()('y', 2)>>> d{'x': 1}

Setdefault: if the key does not exist, the default value is returned and the corresponding dictionary is updated.

>>> d={}>>> d.setdefault('name','N/A')'N/A'>>> d{'name': 'N/A'}>>> d['name']='Gumby'>>> d.setdefault('name','N/A')'Gumby'>>> d{'name': 'Gumby'}

Update updates another dictionary using one dictionary item

>>> d={'x':1,'y':2,'z':3}>>> f={'y':5}>>> d.update(f)>>> d{'y': 5, 'x': 1, 'z': 3}

Values and itervalues alues return values in the dictionary (itervalues return value iterator)

>>> d={}>>> d[1]=1>>> d[2]=2>>> d[3]=3>>> d.values()[1, 2, 3]

The above is a detailed description of several methods in the python dictionary. For more information, see other related articles in the first PHP community!