Python學習筆記2-解析資料

標籤：

Import os; -- Python內建

print(os.getcwd()) -- 獲得當前工作目錄

os.chdir(‘/Users/longlong/Documents‘) -- 轉換到/Users/longlong/Documents目錄

os.path.join(parm1, parm2,...) -- 從一個或多個路徑片段中構造一個路徑名。

os.path.expanduser() -- 用來將包含～符號的路徑擴充為完整的路徑

 

>>> pathname = ‘/Users/pilgrim/diveintopython3/examples/humansize.py‘
>>> os.path.split(pathname)  --(‘/Users/pilgrim/diveintopython3/examples‘, ‘humansize.py‘）羅列目錄內容構造絕對路徑

 

>>> 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>>> 

 

 

列表解析

>>> [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‘]

 

字典解析

>>> 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‘}

 

集合解析

>>> 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}

 

Python學習筆記2-解析資料