Python Dictionary method

This article is referenced from the basic Python Tutorial (second edition)

Operation	Grammar	Example	Results
Build a dictionary	Dict () 1. Creating a dictionary with keyword parameters 2. Building a dictionary with other mappings as parameters	1.d = Dict (name= ' Gumby ', age=42) D 2.items = [(' Name ', ' Gumby '), (' Age ', 42)] D = dict (items) D	{' Age ':, ' name ': ' Gumby '} {' Age ':, ' name ': ' Gumby '}
	Fromkeys () 1. Create a new dictionary for the specified key 2. Call Fromkeys with Dict 3. If you do not want to use none as the default value, you can provide the default value yourself	1.{}.fromkeys ([' Name ', ' age ']) 2.dict.fromkeys ([' Name ', ' age ']) 3.dict.fromkeys ([' Name ', ' age '], ' (unknown) ')	{' Age ': none, ' Name ': none} {' Age ': none, ' Name ': none} {' Age ': ' (unknown) ', ' Name ': ' (unknown) '}
Clear Dictionary	Clear () 1. Clear all items in the dictionary 2. No return value (or the return value is None)	1.d = {' name ': ' Gumby ', ' Age ': 42} Value = D.clear () D 2. Print value	{} None
Shallow copy	Copy () 1. Returns a new dictionary with the same key-value pair 2. The original dictionary is not affected when a value is substituted in the replica 3. When you modify a value (not a replacement) in a replica The original dictionary will change	1.x = {' username ': ' admin ', ' machines ': [' foo ', ' Bar ', ' Baz ']} y = x.copy () y   2.y[' username '] = ' mhl ' y x   3.y[' machines '].remove (' bar ') Y x	{' username ': ' admin ', ' machines ': [' foo ', ' Bar ', ' Baz ']} & nbsp; {' username ': ' MHL ', ' Machines ': [' foo ', ' Bar ', ' Baz '} {' username ': ' admin ', ' machines ': [' foo ', ' Bar ', ' Baz '}     {' username ': ' MHL ', ' Machines ': [' foo ', ' Baz '}} {' username ': ' admin ', ' machines ': [' foo ', ' Baz '}}
Deep copy	Deepcopy () 1. The original dictionary is unaffected when a value is modified (not replaced) in the replica	From copy import deepcopy D = {' names ': [' Alfred ', ' Bertrand '} Deep = deepcopy (d) deep[' names '].append (' Clive ') Deep D	{' names ': [' Alfred ', ' Bertrand ', ' Clive ']} {' names ': [' Alfred ', ' Bertrand ']}
accessing dictionary items/setting default values	Get () 1. More relaxed access to the dictionary entry, access to a nonexistent key, no error 2. Customizing default values	1.d = {} Print d.get (' name ') 2.d.get (' name ', ' N/A ')	None ' N/A '
	SetDefault () 1. More relaxed access to the dictionary entry, access to a nonexistent key, no error 2. Customizing default values 3. When the key is present, return the corresponding value	1.d = {} Print D.setdefault (' name ') 2.D = {} D.setdefault (' name ', ' N/A ') 3.d = {' name ': ' Gumby '} D.setdefault (' name ', ' N/A ')	None ' N/A ' ' Gumby '
Check key	Has_key () 1.d.has_key (key) equivalent to K in D	D = {} D.has_key (' name ') d[' name '] = ' Eric ' D.has_key (' name ')	False True
Iteration	Iteration of keys: Keys () and Iterkeys () 1.keys () returns the keys in the dictionary as a list 2.iterkeys () The iterator that returns the key	1.d = {' title ': ' Python Web Site ', ' url ': ' http://www.python.org ', ' spam ': 0} D.keys () 2.ik = D.iterkeys () Ik List (IK)	[' url ', ' spam ', ' title '] <dictionary-keyiterator Object at 0x0000000002c1fa98> [' url ', ' spam ', ' title ']
	Iterations of Values: Values () and itervalues () 1.values () returns the values in the dictionary as a list 2.itervalues () iterator that returns a value	1.d = {' title ': ' Python Web Site ', ' url ': ' http://www.python.org ', ' spam ': 0} D.values () 2.IV = D.itervalues () iv List (iv)	[' http://www.python.org ', 0, ' python Web Site '] <dictionary-valueiterator Object at 0x0000000002c1fae8> [' http://www.python.org ', 0, ' python Web Site ']
	Iteration of key-value pairs: items () and Iteritems () 1.items () returns all dictionary entries as a list 2.iteritems () returns an iterator for all dictionary items	1.d = {' title ': ' Python Web Site ', ' url ': ' http://www.python.org ', ' spam ': 0} D.items () 2.it = D.iteritems () It List (IT)	[(' url ', ' http://www.python.org '), (' spam ', 0), (' title ', ' Python Web Site ')] <dictionary-itemiterator Object at 0x0000000002c1fb38> [(' url ', ' http://www.python.org '), (' spam ', 0), (' title ', ' Python Web Site ')]
Removed from	Pop () 1. Get the value of the given key and remove the key-value pair from the dictionary	D = {' X ': 1, ' Y ': 2| D.pop (' x ') D	1 {' Y ': 2}
	Popitem () 1. Remove random items	d = {' URL ': ' http://www.python.org ', ' spam ': 0, ' title ': ' Python Web Site '} D.popitem () D	(' url ', ' http://www.python.org ') {' spam ': 0, ' title ': ' Python Web Site '}
Update	Update () 1. Update another dictionary with one dictionary item	D = {' title ': ' Python Web Site ', ' url ': ' http://www.python.org ', ' changed ': ' Mar 22:09:15 MET 2008 '} x = {' title ': ' Python Language Website '} D.update (x) D	{' URL ': ' http://www.python.org ', ' changed ': ' Mar 22:09:15 MET ', ' title ': ' Python Language Website '}

Python Dictionary method