Talking about data parsing in Python, talking about python Parsing

Talking about data parsing in Python, talking about python Parsing

Import OS; -- Python built-in
Print (OS. getcwd () -- get the current working directory
OS. chdir ('/Users/longlong/documents') -- convert to the/Users/longlong/Documents directory.
OS. path. join (parm1, parm2,...) -- constructs a path name from one or more path fragments.
OS. path. expanduser () -- used to include ~ The path of the symbol is expanded to the complete path.

Copy codeThe Code is as follows:
>>> Pathname = '/Users/pilgrim/dive1_python3/examples/humansize. py'
>>> OS. path. split (pathname) -- ('/Users/pilgrim/dive1_python3/examples', 'humansize. py') list the directory content to construct an absolute path

Copy codeThe Code is as follows:
>>> Import OS
>>> Print (OS. getcwd ())
/Users/longlong/Documents
>>> OS. chdir ("./python /")
>>> OS. getcwd ()
'/Users/longlong/Documents/python'
>>> Print (OS. path. realpath ('whileloop. py ')
)
/Users/longlong/Documents/python/whileloop. py
>>> Print (OS. path. realpath ("whileloop. py "))
/Users/longlong/Documents/python/whileloop. py
>>>

List Parsing

Copy codeThe Code is as follows:
>>> [OS. path. realpath (f) for f in glob. glob ("*. py")]
['/Users/longlong/Documents/python/indices_over_two_objects.py', '/Users/longlong/Documents/python/loops_over_indices.py ', '/Users/longlong/Documents/python/while_loops.py'] <br>
>>> [F for f in glob. glob ("*. py") if OS. stat (f). st_size> 700]
['Indices _ over_two_objects.py ', 'while _ loops. py']
1
 
 

Dictionary Parsing

>>> metadat_dict = { f:os.stat(f) for f in glob.glob('*.py')} >>> type(metadat_dict)<class 'dict'> >>> list(metadat_dict.keys())['indices_over_two_objects.py', 'while_loops.py', 'loops_over_indices.py'] >>> metadat_dict['indices_over_two_objects.py'].st_size871

>>> list(metadat_dict.keys())['indices_over_two_objects.py', 'while_loops.py', 'loops_over_indices.py'] >>> a_dict = {'a':1, 'b':2,'c':3}>>> {value:key for key,value in a_dict.items()}{1: 'a', 2: 'b', 3: 'c'} 

Set Parsing

>>> a_set = set(range(10))>>> a_set{0, 1, 2, 3, 4, 5, 6, 7, 8, 9} >>> {x**2 for x in a_set}{0, 1, 64, 4, 36, 9, 16, 49, 81, 25} >>> {x for x in a_set if x%2 == 0 }{0, 8, 2, 4, 6} >>> {2**x for x in range(10)}{32, 1, 2, 64, 4, 128, 256, 512, 8, 16}

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