[从头学python] 第04节 集合模块collections

本节目标：
(1) 学习标准库abc, binascii, binhex, builtins, calendar, chunk, collections, formatter,

fileinput, importlib模块

实现步骤：

abc--抽象基础类可以作为mixin，带着它的功能投入到任何类中间去。

>>> import abc
>>> help(abc)
Help on module abc:

NAME
    abc - Abstract Base Classes (ABCs) according to PEP 3119.

CLASSES
    builtins.classmethod(builtins.object)
        abstractclassmethod
    builtins.property(builtins.object)
        abstractproperty
    builtins.staticmethod(builtins.object)
        abstractstaticmethod
    builtins.type(builtins.object)
        ABCMeta
    
    class ABCMeta(builtins.type)
     |  Metaclass for defining Abstract Base Classes (ABCs).
     |  
     |  Use this metaclass to create an ABC.  An ABC can be subclassed
     |  directly, and then acts as a mix-in class.  You can also register
     |  unrelated concrete classes (even built-in classes) and unrelated
     |  ABCs as 'virtual subclasses' -- these and their descendants will
     |  be considered subclasses of the registering ABC by the built-in
     |  issubclass() function, but the registering ABC won't show up in
     |  their MRO (Method Resolution Order) nor will method
     |  implementations defined by the registering ABC be callable (not
     |  even via super()).
     |  
     |  Method resolution order:
     |      ABCMeta
     |      builtins.type
     |      builtins.object
	 
>>> dir(abc)
['ABCMeta', 'WeakSet', '__builtins__', '__cached__', '__doc__', '__file__', 
'__initializing__', '__loader__', '__name__', '__package__', 'abstractclassmethod', 
'abstractmethod', 'abstractproperty', 'abstractstaticmethod']

binascii可以在二进制和ascii中间转换

>>> import binascii
>>> help(binascii)
Help on built-in module binascii:

NAME
    binascii - Conversion between binary data and ASCII

CLASSES
    builtins.Exception(builtins.BaseException)
        Incomplete
    builtins.ValueError(builtins.Exception)
        Error
    
    class Error(builtins.ValueError)
     |  Method resolution order:
     |      Error
     |      builtins.ValueError
     |      builtins.Exception
     |      builtins.BaseException
     |      builtins.object
     |  
	 
>>> dir(binascii)
['Error', 'Incomplete', '__doc__', '__loader__', '__name__', '__package__', 'a2b_base64', 
'a2b_hex', 'a2b_hqx', 'a2b_qp', 'a2b_uu', 'b2a_base64', 'b2a_hex', 'b2a_hqx', 'b2a_qp', 
'b2a_uu', 'crc32', 'crc_hqx', 'hexlify', 'rlecode_hqx', 'rledecode_hqx', 'unhexlify']

binhex是文件格式的压缩/解压缩用的，和binascii完全没有相同点

>>> help(binhex)
Help on module binhex:

NAME
    binhex - Macintosh binhex compression/decompression.

DESCRIPTION
    easy interface:
    binhex(inputfilename, outputfilename)
    hexbin(inputfilename, outputfilename)

CLASSES
    builtins.Exception(builtins.BaseException)
        Error
    
    class Error(builtins.Exception)
     |  Method resolution order:
     |      Error
     |      builtins.Exception
     |      builtins.BaseException
     |      builtins.object
     |  

>>> dir(binhex)
['BinHex', 'Error', 'FInfo', 'HexBin', 'LINELEN', 'REASONABLY_LARGE', 'RUNCHAR', '_DID_DATA', 
'_DID_HEADER', '_DID_RSRC', '_Hqxcoderengine', '_Hqxdecoderengine', '_Rlecoderengine', 
'_Rledecoderengine', '__all__', '__builtins__', '__cached__', '__doc__', '__file__', 
'__initializing__', '__loader__', '__name__', '__package__', 'binascii', 'binhex', 
'getfileinfo', 'hexbin', 'io', 'openrsrc', 'os', 'struct']	 

builtins是不需要加载的嫡系内置函数，已经在前几节仔细看过

>>> import builtins
>>> help(builtins)
Help on built-in module builtins:

NAME
    builtins - Built-in functions, exceptions, and other objects.

DESCRIPTION
    Noteworthy: None is the `nil' object; Ellipsis represents `...' in slices.

CLASSES
    object
        BaseException
            Exception
                ArithmeticError
                    FloatingPointError
                    OverflowError
                    ZeroDivisionError
                AssertionError
                AttributeError
                BufferError
                EOFError
                ImportError
                LookupError
                    IndexError
                    KeyError
                MemoryError
                NameError
                    UnboundLocalError
                OSError
                    BlockingIOError
                    ChildProcessError
                    ConnectionError
                        BrokenPipeError
                        ConnectionAbortedError
                        ConnectionRefusedError
                        ConnectionResetError
                    FileExistsError
                    FileNotFoundError
                    InterruptedError
                    IsADirectoryError
                    NotADirectoryError
                    PermissionError
                    ProcessLookupError
                    TimeoutError
                ReferenceError
                RuntimeError
                    NotImplementedError
                StopIteration
                SyntaxError
                    IndentationError
                        TabError
                SystemError
                TypeError
                ValueError
                    UnicodeError
                        UnicodeDecodeError
                        UnicodeEncodeError
                        UnicodeTranslateError
                Warning
                    BytesWarning
                    DeprecationWarning
                    FutureWarning
                    ImportWarning
                    PendingDeprecationWarning
                    ResourceWarning
                    RuntimeWarning
                    SyntaxWarning
                    UnicodeWarning
                    UserWarning
            GeneratorExit
            KeyboardInterrupt
            SystemExit
        bytearray
        bytes
        classmethod
        complex
        dict
        enumerate
        filter
        float
        frozenset
        int
            bool
        list
        map
        memoryview
        property
        range
        reversed
        set
        slice
        staticmethod
        str
        super
        tuple
        type
        zip
    
    class ArithmeticError(Exception)
     |  Base class for arithmetic errors.
     |  
     |  Method resolution order:
     |      ArithmeticError
     |      Exception
     |      BaseException
     |      object
	 
>>> dir(builtins)
['ArithmeticError', 'AssertionError', 'AttributeError', 'BaseException', 'BlockingIOError', 
'BrokenPipeError', 'BufferError', 'BytesWarning', 'ChildProcessError', 
'ConnectionAbortedError', 'ConnectionError', 'ConnectionRefusedError', 
'ConnectionResetError', 'DeprecationWarning', 'EOFError', 'Ellipsis', 'EnvironmentError', 
'Exception', 'False', 'FileExistsError', 'FileNotFoundError', 'FloatingPointError', 
'FutureWarning', 'GeneratorExit', 'IOError', 'ImportError', 'ImportWarning', 
'IndentationError', 'IndexError', 'InterruptedError', 'IsADirectoryError', 'KeyError', 
'KeyboardInterrupt', 'LookupError', 'MemoryError', 'NameError', 'None', 'NotADirectoryError'
, 'NotImplemented', 'NotImplementedError', 'OSError', 'OverflowError', 
'PendingDeprecationWarning', 'PermissionError', 'ProcessLookupError', 'ReferenceError', 
'ResourceWarning', 'RuntimeError', 'RuntimeWarning', 'StopIteration', 'SyntaxError', 
'SyntaxWarning', 'SystemError', 'SystemExit', 'TabError', 'TimeoutError', 'True', 
'TypeError', 'UnboundLocalError', 'UnicodeDecodeError', 'UnicodeEncodeError', 'UnicodeError'
, 'UnicodeTranslateError', 'UnicodeWarning', 'UserWarning', 'ValueError', 'Warning', 
'WindowsError', 'ZeroDivisionError', '_', '__build_class__', '__debug__', '__doc__', 
'__import__', '__loader__', '__name__', '__package__', 'abs', 'all', 'any', 'ascii', 'bin', 
'bool', 'bytearray', 'bytes', 'callable', 'chr', 'classmethod', 'compile', 'complex', 
'copyright', 'credits', 'delattr', 'dict', 'dir', 'divmod', 'enumerate', 'eval', 'exec', 
'exit', 'filter', 'float', 'format', 'frozenset', 'getattr', 'globals', 'hasattr', 'hash', 
'help', 'hex', 'id', 'input', 'int', 'isinstance', 'issubclass', 'iter', 'len', 'license', 
'list', 'locals', 'map', 'max', 'memoryview', 'min', 'next', 'object', 'oct', 'open', 'ord',
 'pow', 'print', 'property', 'quit', 'range', 'repr', 'reversed', 'round', 'set', 'setattr',
 'slice', 'sorted', 'staticmethod', 'str', 'sum', 'super', 'tuple', 'type', 'vars', 'zip']

日历类calendar，完全是一个小工具

>>> import calendar
>>> help(calendar)
Help on module calendar:

NAME
    calendar - Calendar printing functions

DESCRIPTION
    Note when comparing these calendars to the ones printed by cal(1): By
    default, these calendars have Monday as the first day of the week, and
    Sunday as the last (the European convention). Use setfirstweekday() to
    set the first day of the week (0=Monday, 6=Sunday).

CLASSES
    builtins.ValueError(builtins.Exception)
        IllegalMonthError
        IllegalWeekdayError
    
    class IllegalMonthError(builtins.ValueError)
     |  # Exceptions raised for bad input
     |  
     |  Method resolution order:
     |      IllegalMonthError
     |      builtins.ValueError
     |      builtins.Exception
     |      builtins.BaseException
     |      builtins.object
	 

 >>> dir(calendar)
['Calendar', 'EPOCH', 'FRIDAY', 'February', 'HTMLCalendar', 'IllegalMonthError', 
'IllegalWeekdayError', 'January', 'LocaleHTMLCalendar', 'LocaleTextCalendar', 'MONDAY', 
'SATURDAY', 'SUNDAY', 'THURSDAY', 'TUESDAY', 'TextCalendar', 'WEDNESDAY', '_EPOCH_ORD', 
'__all__', '__builtins__', '__cached__', '__doc__', '__file__', '__initializing__', 
'__loader__', '__name__', '__package__', '_colwidth', '_locale', '_localized_day', 
'_localized_month', '_spacing', 'c', 'calendar', 'datetime', 'day_abbr', 'day_name', 
'different_locale', 'error', 'firstweekday', 'format', 'formatstring', 'isleap', 'leapdays',
 'main', 'mdays', 'month', 'month_abbr', 'month_name', 'monthcalendar', 'monthrange', 
 'prcal', 'prmonth', 'prweek', 'setfirstweekday', 'sys', 'timegm', 'week', 'weekday', 
 'weekheader']
 

chunk类是用来读取tiff, rmff等类型文件的数据的，是文件的数据块。

>>> import chunk
>>> help(chunk)
Help on module chunk:

NAME
    chunk - Simple class to read IFF chunks.

DESCRIPTION
    An IFF chunk (used in formats such as AIFF, TIFF, RMFF (RealMedia File
    Format)) has the following structure:
    
    +----------------+
    | ID (4 bytes)   |
    +----------------+
    | size (4 bytes) |
    +----------------+
    | data           |
    | ...            |
    +----------------+
    
    The ID is a 4-byte string which identifies the type of chunk.
    
    The size field (a 32-bit value, encoded using big-endian byte order)
    gives the size of the whole chunk, including the 8-byte header.
    
    Usually an IFF-type file consists of one or more chunks.  The proposed
    usage of the Chunk class defined here is to instantiate an instance at
    the start of each chunk and read from the instance until it reaches
    the end, after which a new instance can be instantiated.  At the end
    of the file, creating a new instance will fail with a EOFError
    exception.
    
    Usage:
    while True:
        try:
            chunk = Chunk(file)
        except EOFError:
            break
        chunktype = chunk.getname()
        while True:
            data = chunk.read(nbytes)
            if not data:
                pass
            # do something with data
    
    The interface is file-like.  The implemented methods are:
    read, close, seek, tell, isatty.
    Extra methods are: skip() (called by close, skips to the end of the chunk),
    getname() (returns the name (ID) of the chunk)
    
    The __init__ method has one required argument, a file-like object
    (including a chunk instance), and one optional argument, a flag which
    specifies whether or not chunks are aligned on 2-byte boundaries.  The
    default is 1, i.e. aligned.

CLASSES
    builtins.object
        Chunk
		
>>> dir(chunk)
['Chunk', '__builtins__', '__cached__', '__doc__', '__file__', '__initializing__', 
'__loader__', '__name__', '__package__']

集合类collections有许多子类，具体怎么用要仔细研究

>>> import collections
>>> help(collections)
Help on package collections:

NAME
    collections

PACKAGE CONTENTS
    __main__
    abc

CLASSES
    builtins.dict(builtins.object)
        Counter
        OrderedDict
        defaultdict
    builtins.object
        deque
        collections.abc.Callable
        collections.abc.Container
        collections.abc.Hashable
        collections.abc.Iterable
            collections.abc.Iterator
        collections.abc.Sized
            collections.abc.Mapping(collections.abc.Sized, collections.abc.Iterable, collections.abc.Container)
                collections.abc.MutableMapping
                    ChainMap
                    UserDict
            collections.abc.MappingView
                collections.abc.ItemsView(collections.abc.MappingView, collections.abc.Set)
                collections.abc.KeysView(collections.abc.MappingView, collections.abc.Set)
                collections.abc.ValuesView
            collections.abc.Sequence(collections.abc.Sized, collections.abc.Iterable, collections.abc.Container)
                UserString
                collections.abc.ByteString
                collections.abc.MutableSequence
                    UserList
            collections.abc.Set(collections.abc.Sized, collections.abc.Iterable, collections.abc.Container)
                collections.abc.MutableSet
    
    class ByteString(Sequence)
     |  This unifies bytes and bytearray.
     |  
     |  XXX Should add all their methods.
     |  
     |  Method resolution order:
     |      ByteString
     |      Sequence
     |      Sized
     |      Iterable
     |      Container
     |      builtins.object

>>> dir(collections)
['ByteString', 'Callable', 'ChainMap', 'Container', 'Counter', 'Hashable', 'ItemsView', 
'Iterable', 'Iterator', 'KeysView', 'Mapping', 'MappingView', 'MutableMapping', 
'MutableSequence', 'MutableSet', 'OrderedDict', 'Sequence', 'Set', 'Sized', 'UserDict', 
'UserList', 'UserString', 'ValuesView', '_Link', '__all__', '__builtins__', '__cached__', 
'__doc__', '__file__', '__initializing__', '__loader__', '__name__', '__package__', 
'__path__', '_chain', '_class_template', '_count_elements', '_eq', '_field_template', 
'_heapq', '_iskeyword', '_itemgetter', '_proxy', '_recursive_repr', '_repeat', 
'_repr_template', '_starmap', '_sys', 'abc', 'collections', 'defaultdict', 'deque', 
'namedtuple']

>>> dir(collections.ByteString)
['__abstractmethods__', '__class__', '__contains__', '__delattr__', '__dir__', '__doc__', 
'__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__gt__', '__hash__', 
'__init__', '__iter__', '__le__', '__len__', '__lt__', '__module__', '__ne__', '__new__', 
'__reduce__', '__reduce_ex__', '__repr__', '__reversed__', '__setattr__', '__sizeof__', 
'__slots__', '__str__', '__subclasshook__', '_abc_cache', '_abc_negative_cache', 
'_abc_negative_cache_version', '_abc_registry', 'count', 'index']

>>> dir(collections.Hashable)
['__abstractmethods__', '__class__', '__delattr__', '__dir__', '__doc__', '__eq__', 
'__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__le__', 
'__lt__', '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', 
'__setattr__', '__sizeof__', '__slots__', '__str__', '__subclasshook__', '_abc_cache', 
'_abc_negative_cache', '_abc_negative_cache_version', '_abc_registry']

批量文件操作，使用fileinput。

>>> import fileinput
>>> help(fileinput)
Help on module fileinput:

NAME
    fileinput - Helper class to quickly write a loop over all standard input files.

DESCRIPTION
    Typical use is:
    
        import fileinput
        for line in fileinput.input():
            process(line)
    
    This iterates over the lines of all files listed in sys.argv[1:],
    defaulting to sys.stdin if the list is empty.  If a filename is '-' it
    is also replaced by sys.stdin.  To specify an alternative list of
    filenames, pass it as the argument to input().  A single file name is
    also allowed.

>>> dir(fileinput)
['DEFAULT_BUFSIZE', 'FileInput', '__all__', '__builtins__', '__cached__', '__doc__', 
'__file__', '__initializing__', '__loader__', '__name__', '__package__', '_state', '_test', 
'close', 'filelineno', 'filename', 'fileno', 'hook_compressed', 'hook_encoded', 'input', 
'isfirstline', 'isstdin', 'lineno', 'nextfile', 'os', 'sys']

fornatter可以设置writer的格式

>>> import formatter
>>> help(formatter)
Help on module formatter:

NAME
    formatter - Generic output formatting.

DESCRIPTION
    Formatter objects transform an abstract flow of formatting events into
    specific output events on writer objects. Formatters manage several stack
    structures to allow various properties of a writer object to be changed and
    restored; writers need not be able to handle relative changes nor any sort
    of ``change back'' operation. Specific writer properties which may be
    controlled via formatter objects are horizontal alignment, font, and left
    margin indentations. A mechanism is provided which supports providing
    arbitrary, non-exclusive style settings to a writer as well. Additional
    interfaces facilitate formatting events which are not reversible, such as
    paragraph separation.
    
    Writer objects encapsulate device interfaces. Abstract devices, such as
    file formats, are supported as well as physical devices. The provided
    implementations all work with abstract devices. The interface makes
    available mechanisms for setting the properties which formatter objects
    manage and inserting data into the output.

CLASSES
    builtins.object
        AbstractFormatter
        NullFormatter
        NullWriter
            AbstractWriter
            DumbWriter
    
    class AbstractFormatter(builtins.object)
     |  The standard formatter.
     |  
     |  This implementation has demonstrated wide applicability to many writers,
     |  and may be used directly in most circumstances.  It has been used to
     |  implement a full-featured World Wide Web browser.
	 
>>> dir(formatter)
['AS_IS', 'AbstractFormatter', 'AbstractWriter', 'DumbWriter', 'NullFormatter', 'NullWriter'
, '__builtins__', '__cached__', '__doc__', '__file__', '__initializing__', '__loader__', 
'__name__', '__package__', 'sys', 'test']

>>> dir(formatter.DumbWriter)
['__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', 
'__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__le__', '__lt__', 
'__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__',
 '__sizeof__', '__str__', '__subclasshook__', '__weakref__', 'flush', 'new_alignment', 
 'new_font', 'new_margin', 'new_spacing', 'new_styles', 'reset', 'send_flowing_data', 
 'send_hor_rule', 'send_label_data', 'send_line_break', 'send_literal_data', 
 'send_paragraph']

加载库可以用importlib，但不用也没关系

>>> import importlib
>>> help(importlib)
Help on package importlib:

NAME
    importlib - A pure Python implementation of import.

PACKAGE CONTENTS
    _bootstrap
    abc
    machinery
    util
	
>>> dir(importlib)
['__all__', '__builtins__', '__cached__', '__doc__', '__file__', '__import__', 
'__initializing__', '__loader__', '__name__', '__package__', '__path__', '_bootstrap', 
'_imp', '_r_long', '_w_long', 'abc', 'find_loader', 'import_module', 'invalidate_caches', 
'machinery', 'sys']

这些模块只有到必须要用时才会去看它们函数调用的语法，平时一般也用不上。

本节到此结束。