[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 ASCIICLASSES    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 functionsDESCRIPTION    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    collectionsPACKAGE CONTENTS    __main__    abcCLASSES    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。