From getting started with python (DAY 2 ),

From getting started with python (DAY 2 ),

1. dictionary replication:

Dict = {'name': 'wang', 'sex': 'M', 'age': 34, 'job ': 'It'} info = dict # Alias (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 the second layer is associated) import copycopy. copy () # shadow 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__)

Articles you may be interested in:

• Python Dictionary operations
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• Dictionary details in python
• Examples of conversion between dictionaries and JSON in Python
• Python uses the dictionary dict to determine whether a specified key value exists
• Use the update () method for dictionary operations in Python
• Use the values () method to return the value of the dictionary key in Python
• How to extract the dictionary key list using python
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