1, the dictionary creation
(1)} and {created by the dictionary dict ()
>>> a = {'name':'gjr','age':32,'job':'dataAnalysize'}
>>> b = dict(name='gjr',age=32,job='dataAnalyze')
>>> a
{'name': 'gjr', 'age': 32, 'job': 'dataAnalysize'}
>>> b
{'name': 'gjr', 'age': 32, 'job': 'dataAnalyze'}
>>> c = dict([("name","gjr"),("age",32)])
>>> c
{'name': 'gjr', 'age': 32}
>>> d = {}
>>> e = dict()
(2)) to create a dictionary object by zip (
>>> k = ['name','age','job']
>>> v = ['gjr',32,'teacher']
>>> d =dict(zip(k,v))
>>> d
{'name': 'gjr', 'age': 32, 'job': 'teacher'}
(3) create value empty dictionary by fromkeys
>>> a = dict.fromkeys(['name','age','job'])
>>> a
{'name': None, 'age': None, 'job': None}
2, the dictionary access
(1) Access by [Key] 'value'. If the key does not exist, an exception is thrown
>>> d
{'name': 'gjr', 'age': 32, 'job': 'teacher'}
>>> d['name']
'gjr'
>>> d['aa']
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
KeyError: 'aa'
(2) obtained by the get () method 'value'. Recommended Use. Advantages are: the absence of the specified key, returns None, can also set the default object returned key does not exist.
>>> d
{'name': 'gjr', 'age': 32, 'job': 'teacher'}
>>> d.get('age')
32
>>> d.get('aa','donot known')
'donot known'
(3) a list of all key-value pairs
>>> d
{'name': 'gjr', 'age': 32, 'job': 'teacher'}
>>> d.items()
dict_items([('name', 'gjr'), ('age', 32), ('job', 'teacher')]
(4) List of all keys, all values are listed
>>> d
{'name': 'gjr', 'age': 32, 'job': 'teacher'}
>>> d.keys()
dict_keys(['name', 'age', 'job'])
>>> d.values()
dict_values(['gjr', 32, 'teacher'])
(5) len () to get the number of key-value pairs
(6) detecting whether or not a [key] in the dictionary
>>> d
{'name': 'gjr', 'age': 32, 'job': 'teacher'}
>>> 'name' in d
True