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Python Programming – Dictionary Methods
Dictionary methods
The following are some dictionary methods supported by Python.
diet . clear ( ) Removes all items from the dictionary. >>> a= { ' Name ' : ' Zara ' , ' Age ' : 7 } >>> len ( a ) 2 >>> a . clear ( ) >>> len ( a ) 0
diet. copy ( )
Returns a copy of the dictionary.
>>> dict1 = { ' Name ' : ' Zara ' , ' Age ' : 7 ] >>> dict2=dict1 . copy ( ) >>> dict2 { ' Age ' : 7 , ' Name ' : ' Zara ' }
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diet. fromkeys ( seq [ , value ] )
Create a new dictionary with keys from seq and values set to value (default as None).
>>> seq= ( ' name ' , ' age ' , ' gender ' ) >>> a=dict . fromkeys ( seq ) >>> a { ' gender ' : None , ' age ' : None , ' name ' : None } >>> a=a.fromkeys ( seq , 10 ) >>> a { ' gender ' : 10 , ' age ' : 10 , ' name ' : 10 }
diet . get ( key [ , default ] )
Return the value for the key, if the key is in the dictionary, else default. If the default is not given, the default is None.
>>> a= { ' Name ' : ' Zara ' , ' Age ' : 7 } >>> a.get ( ' Age ' ) 7 >>> a. get ( ' Gender ' , ' Never ' ) ' Never ' >>> print a.get ( ' Gender ' ) None
diet.has_key ( key )
Test for the presence of a key in the dictionary. Returns True, if the key is present in the dictionary, otherwise False.
>>> a= { ' Name ' : ' Zara ' , ' Age ' : 7 } >>> a.has_key ( ' Age ' ) True >>> a.has_key ( ' Gender ' ) False
diet.items ( )
Returns a list of dictionary’s key-value tuple pairs.
>>> a= { ' Name ' : ' Zara ' , ' Age ' : 7 } >>> a . items ( ) [ ( ' age ' , 7 ) , ( ' Name ' , ' Zara ' ) ]
diet.iteritems ( )
Returns an iterator over the dictionary’s key-value pairs.
>>> a= { ' Gender ' : ' Female ' , ' Age 1 : 7 , ' Hair color ' : None , ' Name ' : ' Zara ' } >>> for b in a . iteritems ( ) : . . . print ' { 0 } - - - -{ 1 } ' . format ( b [ 0 ] , b [ 1 ] ) . . . Gender - - - -Female Age - - - - 7 Hair color- - - - None1 Name- - - - Zara
diet.iterkeys ( )
Returns an iterator over the dictionary’s keys.
>>> a= { 1 Gender 1 : ’ Female ' , ' Age ' : 7 , ' Hair color ' : None , ' Name ' : ' Zara ' } >>> for b in a.iterkeys ( ) : . . . print b . . . Gender Age Hair color Name
diet.itervalues ( )
Returns an iterator over the dictionary’s values.
>>> a= { 1 Gender ' : ' Female ' , ' Age ' : 7 , ' Hair color ' : None , ' Name ' : ' Zara ' } >>> for b in a.itervalues ( ) : . . . print b . . . Female 7 None Zara
diet.keys ( )
Returns list of dictionary keys.
>>> a= { ' Name ' : ' Zara ' , ' Age ' : 7 } >>> a . keys ( ) [ ' Age ' , ' Name ' ]
diet.pop ( key [ , default ] )
If key is.in the dictionary, remove it and return its value, else return default. If default is not given and key is not in the dictionary, a KeyError is raised.
>>> a= { ' Gender ' : ' Female ' , ' Age ' : 7 , ' Hair color ' : None , ' Name ' : ' Zara ' } >>> a . pop ( ' Age ' , 15 ) 7 >>> a . pop ( ' Age ' , 15 ) 15 >>> a { ' Gender ' : ' Female ' , ' Hair color ' : None , ' Name ' : ' Zara ' }
diet. popitem ( )
Remove and return an arbitrary key-value pair from the dictionary. If the dictionary is empty, calling popitem () raises an KeyError exception.
>>> a= { ' Gender ' : ' Female ' , ' Age ' : 7 , ' Hair color ' : None , ' Name ' : ' Zara ' } >>> a . popitem ( ) ( ' Gender ' , ' Female ' ) >>> a . popitem ( ) ( ' Age ' , 7 ) >>> a { ' Hair color ' : None , ' Name ' : ' Zara ' }
diet . setdefault ( key [ , default ] )
If key is in the dictionary, return its value. If not, insert key with a value of default and return default. The default defaults to None.
>>> a= { ' Name ' : ' Zara ' , ' Age ' : 7 } >>> a . setdefault ( ' Age ' , 15 ) 7 >>> a . setdefault ( ' Gender ' , ' Female ' ) ' Female ' >>> a . setdefault ( ' Hair color ' ) >>> a { ' Gender ' : ' Female ' , ' Age ' : 7 , ' Hair color ' : None , ' Name ' : ' Zara ' }
diet.update ( [ other ] )
Update the dictionary with the key-value pairs from other, overwriting existing keys, and returns None. The method accepts either another dictionary object or an iterable of key-value pairs (as tuples or other iterables of length two). If keyword arguments are specified, the dictionary is then updated with those key-value pairs.
>>> dict1= { ' Name ' : ' Zara ' , ' Age ' : 7 } >>> dict2= { ' Gender ' : ' female ' } >>> dict1 . update ( dict2 ) >>> dict1 . update ( hair_color= ' black ' , eye_color= ' blue ' ) >>> dict1 { ' eye_color ' : ' blue ' , ' Gender ' : ' female ' , ' Age ' : 7 , ' Name ' : ' Zara ' , ' hair_color ' : ' black ' }
diet . values ( )
Return list of dictionary values.
>>> a= { ' Name ' : ' Zara ' , ' Age ' : 7 } >>> a . values ( ) [ 7, ' Zara ' ]