Python3dict (dictionary) description

This article explains how to use python to perform operations on the dict Dictionary. Clear (clear dictionary content)

Stu = {'num1': 'Tom ', 'num2': 'Lucy', 'num3': 'Sam ',} print (stu. clear () # output: None

Copy (copy dictionary)

stu = {    'num1':'Tom',    'num2':'Lucy',    'num3':'Sam',}stu2 = stu.copy()print(stu2)

Fromkeys (specify a list and use the values in the list as the dictionary key to generate a dictionary)

Name = ['Tom ', 'Lucy', 'Sam '] print (dict. fromkeys (name) print (dict. fromkeys (name, 25) # specify the default value # output: {'Tom ': None, 'Lucy': None, 'Sam ': None} # {'Tom': 25, 'Lucy ': 25, 'Sam': 25}

Get (specify the key to obtain the corresponding value)

Stu = {'num1': 'Tom ', 'num2': 'Lucy', 'num3': 'Sam ',} print (stu. get ('num2') # output: Lucy

Items (return the list of "key-value pairs consisting of elements)

Stu = {'num1': 'Tom ', 'num2': 'Lucy', 'num3': 'Sam ',} print (stu. items () # output: dict_items ([('num2', 'Lucy '), ('num3', 'Sam'), ('num1 ', 'Tom ')])

Keys)

Stu = {'num1': 'Tom ', 'num2': 'Lucy', 'num3': 'Sam ',} print (stu. keys () # output: dict_keys (['num3', 'num1', 'num2'])

Pop (get the value of the specified key and delete it in the dictionary)

Stu = {'num1': 'Tom ', 'num2': 'Lucy', 'num3': 'Sam ',} name = stu. pop ('num2') print (name, stu) # output: Lucy {'num1': 'Tom ', 'num3': 'Sam '}

Popitem (randomly obtain a key-value pair and delete it in the dictionary)

Stu = {'num1': 'Tom ', 'num2': 'Lucy', 'num3': 'Sam ',} name = stu. popitem () print (name, stu) # output: ('num2', 'Lucy ') {'num3': 'Sam', 'num1': 'Tom '}

Setdefault (obtain the value of the specified key. if the key does not exist, it is created)

Stu = {'num1': 'Tom ', 'num2': 'Lucy', 'num3': 'Sam ',} name = stu. setdefault ('num5') print (name, stu) # output: None {'num1': 'Tom ', 'num2': 'Lucy', 'num5': None, 'num3': 'Sam '}

Update (add a key-value pair to the dictionary)

Stu = {'num1': 'Tom ', 'num2': 'Lucy', 'num3': 'Sam ',} stu. update ({'num4': 'Ben'}) print (stu) # output: {'num2': 'Lucy ', 'num3': 'Sam', 'num1 ': 'Tom ', 'num4': 'Ben '}

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