Python learning notes (the next day) and python learning notes

Python learning notes (the next day) and python learning notes

 

1. dictionary replication:

Dict = {'name': 'wang', 'sex': 'M', 'age': 34, 'job': 'it '}

Info = dict # Alias (the two dictionaries point to the same address space in the memory)

Info1 = dict. copy () # shadow copy (the first layer of the nested dictionary is independent and associated below the second layer)

Import copy

Copy. copy () # shadow copy

Copy. deepcopy () # deep copy (completely independent)

Note: The associations in the light replication mode are only for the nested objects contained in the dictionary's initial state. Newly Added objects will not

Example:

>>> Dict
{'Info': ['A', 'B', 1, 2], 'job': 'it', 'sex': 'M', 'age ': 40, 'name': 'wang '}
>>> Dict_alias = dict
>>> Dict_copy = copy. copy (dict)
>>> Dict_deep = copy. deepcopy (dict)

# Adding, changing, and deleting the first-level object key values are not affected in light replication and deep Replication

>>> Dict ['age'] = 32

>>> Del dict ['sex']
>>> Dict
{'Info': ['A', 'B', 1, 2], 'job': 'it', 'age': 32, 'name ': 'wang '}
>>> Dict_alias
{'Info': ['A', 'B', 1, 2], 'job': 'it', 'age': 32, 'name ': 'wang '}
>>> Dict_copy
{'Info': ['A', 'B', 1, 2], 'job': 'it', 'age': 40, 'name ': 'wang ', 'sex': 'M '}
>>> Dict_deep
{'Info': ['A', 'B', 1, 2], 'job': 'it', 'age': 40, 'name ': 'wang ', 'sex': 'M '}

# Change or delete the original second-level object key value. The shortest copy is affected, but the deep copy is not affected.

> Dict ['info'] [2] = 100
>>> Dict
{'Info': ['A', 'B', 100, 2], 'job': 'it', 'age': 32, 'name ': 'wang '}
>>> Dict_alias
{'Info': ['A', 'B', 100, 2], 'job': 'it', 'age': 32, 'name ': 'wang '}
>>> Dict_copy
{'Info': ['A', 'B', 100, 2], 'job': 'it', 'age': 40, 'name ': 'wang ', 'sex': 'M '}
>>> Dict_deep
{'Info': ['A', 'B', 1, 2], 'job': 'it', 'age': 40, 'name ': 'wang ', 'sex': 'M '}

# Adding second-level objects will not be affected in light replication and deep Replication

>>> Dict ['new'] = {'A': 1, 'B': 2, 'C': 5}
>>> Dict
{'Info': ['A', 'B', 100, 2], 'name': 'wang', 'age': 32, 'job ': 'it', 'new': {'A': 1, 'C': 5, 'B': 2 }}
>>> Dict_alias
{'Info': ['A', 'B', 100, 2], 'name': 'wang', 'age': 32, 'job ': 'it', 'new': {'A': 1, 'C': 5, 'B': 2 }}
>>> Dict_copy
{'Info': ['A', 'B', 100, 2], 'job': 'it', 'age': 40, 'name ': 'wang ', 'sex': 'M '}
>>> Dict_deep
{'Info': ['A', 'B', 1, 2], 'job': 'it', 'age': 40, 'name ': 'wang ', 'sex': 'M '}

 

2. built-in function description:

_ Name __: the main file is returned; otherwise, the file name is returned, which can be used to determine whether the main file or the import module is used;

_ File __: absolute file path;

_ Doc __: description of the beginning of the file

Example:

'''
Created by 2015-12-18
@ Author: kevin
'''

If _ name _ = '_ main __':
Print ('this is main file ')
Print (_ file __)
Print (_ doc __)