On data parsing in Python

This article is to introduce the data in Python in a centralized way, including list parsing, dictionary parsing, set parsing, and attached to the relevant examples, the need for small partners can refer to.

Import OS; --Python self-belt

Print (OS.GETCWD ())--Get current working directory

Os.chdir ('/users/longlong/documents ')--Convert to/users/longlong/documents directory

Os.path.join (Parm1, Parm2,...)--Constructs a path name from one or more path fragments.

Os.path.expanduser ()--to extend the path containing the ~ symbol to the full path

Copy code code as follows:

>>> pathname = '/users/pilgrim/diveintopython3/examples/humansize.py '

>>> os.path.split (Pathname)--('/users/pilgrim/diveintopython3/examples ', ' humansize.py ') List contents construct absolute path

Copy code code 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 resolution

Copy code code 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 ']

>>> [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

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>>> metadat_dict = {F:os.stat (f) for F in Glob.glob (' *.py ')} >>> type (metadat_dict) <class ' Dict ' &   Gt   >>> list (Metadat_dict.keys ()) [' indices_over_two_objects.py ', ' while_loops.py ', ' loops_over_indices.py '] >>> metadat_dict[' indices_over_two_objects.py '].st_size 871

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>>> 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

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>>> A_set = set (range) >>> a_set {0, 1, 2, 3, 4, 5, 6, 7, 8, 9} >>> {x**2 for x in A_set} {0, 1, 9, 4, >>> {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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