函式¶

pprint.pp(object,stream=None,indent=1,width=80,depth=None,*,compact=False,sort_dicts=False,underscore_numbers=False)¶

Prints the formatted representation ofobject, followed by a newline.This function may be used in the interactive interpreterinstead of theprint() function for inspecting values.Tip: you can reassignprint=pprint.pp for use within a scope.

參數:

• object -- 將被印出的物件。

• stream (file-like object | None) -- A file-like object to which the output will be writtenby calling itswrite() method.IfNone (the default),sys.stdout is used.

• indent (int) -- The amount of indentation added for each nesting level.

• width (int) -- The desired maximum number of characters per line in the output.If a structure cannot be formatted within the width constraint,a best effort will be made.

• depth (int |None) -- The number of nesting levels which may be printed.If the data structure being printed is too deep,the next contained level is replaced by....IfNone (the default), there is no constrainton the depth of the objects being formatted.

• compact (bool) -- Control the way longsequences are formatted.IfFalse (the default),each item of a sequence will be formatted on a separate line,otherwise as many items as will fit within thewidthwill be formatted on each output line.

• sort_dicts (bool) -- IfTrue, dictionaries will be formatted withtheir keys sorted, otherwisethey will be displayed in insertion order (the default).

• underscore_numbers (bool) -- IfTrue,integers will be formatted with the_ character for a thousands separator,otherwise underscores are not displayed (the default).

>>>importpprint>>>stuff=['spam','eggs','lumberjack','knights','ni']>>>stuff.insert(0,stuff)>>>pprint.pp(stuff)[<Recursion on list with id=...>, 'spam', 'eggs', 'lumberjack', 'knights', 'ni']

在 3.8 版被加入.

pprint.pprint(object,stream=None,indent=1,width=80,depth=None,*,compact=False,sort_dicts=True,underscore_numbers=False)¶

Alias forpp() withsort_dicts set toTrue by default,which would automatically sort the dictionaries' keys,you might want to usepp() instead where it isFalse by default.

pprint.pformat(object,indent=1,width=80,depth=None,*,compact=False,sort_dicts=True,underscore_numbers=False)¶

Return the formatted representation ofobject as a string.indent,width,depth,compact,sort_dicts andunderscore_numbers arepassed to thePrettyPrinter constructor as formatting parametersand their meanings are as described in the documentation above.

pprint.isreadable(object)¶

Determine if the formatted representation ofobject is "readable", or can beused to reconstruct the value usingeval(). This always returnsFalsefor recursive objects.

>>>pprint.isreadable(stuff)False

pprint.isrecursive(object)¶

Determine ifobject requires a recursive representation. This function issubject to the same limitations as noted insaferepr() below and may raise anRecursionError if it fails to detect a recursive object.

pprint.saferepr(object)¶

Return a string representation ofobject, protected against recursion insome common data structures, namely instances ofdict,listandtuple or subclasses whose__repr__ has not been overridden. If therepresentation of object exposes a recursive entry, the recursive referencewill be represented as<Recursionontypenamewithid=number>. Therepresentation is not otherwise formatted.

>>>pprint.saferepr(stuff)"[<Recursion on list with id=...>, 'spam', 'eggs', 'lumberjack', 'knights', 'ni']"

PrettyPrinter 物件¶

classpprint.PrettyPrinter(indent=1,width=80,depth=None,stream=None,*,compact=False,sort_dicts=True,underscore_numbers=False)¶

建立一個PrettyPrinter 實例。

Arguments have the same meaning as forpp().Note that they are in a different order, and thatsort_dicts defaults toTrue.

>>>importpprint>>>stuff=['spam','eggs','lumberjack','knights','ni']>>>stuff.insert(0,stuff[:])>>>pp=pprint.PrettyPrinter(indent=4)>>>pp.pprint(stuff)[   ['spam', 'eggs', 'lumberjack', 'knights', 'ni'],    'spam',    'eggs',    'lumberjack',    'knights',    'ni']>>>pp=pprint.PrettyPrinter(width=41,compact=True)>>>pp.pprint(stuff)[['spam', 'eggs', 'lumberjack',  'knights', 'ni'], 'spam', 'eggs', 'lumberjack', 'knights', 'ni']>>>tup=('spam',('eggs',('lumberjack',('knights',('ni',('dead',...('parrot',('fresh fruit',))))))))>>>pp=pprint.PrettyPrinter(depth=6)>>>pp.pprint(tup)('spam', ('eggs', ('lumberjack', ('knights', ('ni', ('dead', (...)))))))

在 3.4 版的變更:新增compact 參數。

在 3.8 版的變更:新增sort_dicts 參數。

在 3.10 版的變更:新增underscore_numbers 參數。

在 3.11 版的變更:No longer attempts to write tosys.stdout if it isNone.

PrettyPrinter 實例有以下方法：

PrettyPrinter.pformat(object)¶

Return the formatted representation ofobject. This takes into account theoptions passed to thePrettyPrinter constructor.

PrettyPrinter.pprint(object)¶

Print the formatted representation ofobject on the configured stream,followed by a newline.

The following methods provide the implementations for the correspondingfunctions of the same names. Using these methods on an instance is slightlymore efficient since newPrettyPrinter objects don't need to becreated.

PrettyPrinter.isreadable(object)¶

Determine if the formatted representation of the object is "readable," or can beused to reconstruct the value usingeval(). Note that this returnsFalse for recursive objects. If thedepth parameter of thePrettyPrinter is set and the object is deeper than allowed, thisreturnsFalse.

PrettyPrinter.isrecursive(object)¶

Determine if the object requires a recursive representation.

This method is provided as a hook to allow subclasses to modify the way objectsare converted to strings. The default implementation uses the internals of thesaferepr() implementation.

PrettyPrinter.format(object,context,maxlevels,level)¶

Returns three values: the formatted version ofobject as a string, a flagindicating whether the result is readable, and a flag indicating whetherrecursion was detected. The first argument is the object to be presented. Thesecond is a dictionary which contains theid() of objects that are part ofthe current presentation context (direct and indirect containers forobjectthat are affecting the presentation) as the keys; if an object needs to bepresented which is already represented incontext, the third return valueshould beTrue. Recursive calls to theformat() method should addadditional entries for containers to this dictionary. The third argument,maxlevels, gives the requested limit to recursion; this will be0 if thereis no requested limit. This argument should be passed unmodified to recursivecalls. The fourth argument,level, gives the current level; recursive callsshould be passed a value less than that of the current call.

範例¶

To demonstrate several uses of thepp() function and its parameters,let's fetch information about a project fromPyPI:

>>>importjson>>>importpprint>>>fromurllib.requestimporturlopen>>>withurlopen('https://pypi.org/pypi/sampleproject/1.2.0/json')asresp:...project_info=json.load(resp)['info']

In its basic form,pp() shows the whole object:

>>>pprint.pp(project_info){'author': 'The Python Packaging Authority', 'author_email': 'pypa-dev@googlegroups.com', 'bugtrack_url': None, 'classifiers': ['Development Status :: 3 - Alpha',                 'Intended Audience :: Developers',                 'License :: OSI Approved :: MIT License',                 'Programming Language :: Python :: 2',                 'Programming Language :: Python :: 2.6',                 'Programming Language :: Python :: 2.7',                 'Programming Language :: Python :: 3',                 'Programming Language :: Python :: 3.2',                 'Programming Language :: Python :: 3.3',                 'Programming Language :: Python :: 3.4',                 'Topic :: Software Development :: Build Tools'], 'description': 'A sample Python project\n'                '=======================\n'                '\n'                'This is the description file for the project.\n'                '\n'                'The file should use UTF-8 encoding and be written using '                'ReStructured Text. It\n'                'will be used to generate the project webpage on PyPI, and '                'should be written for\n'                'that purpose.\n'                '\n'                'Typical contents for this file would include an overview of '                'the project, basic\n'                'usage examples, etc. Generally, including the project '                'changelog in here is not\n'                'a good idea, although a simple "What\'s New" section for the '                'most recent version\n'                'may be appropriate.', 'description_content_type': None, 'docs_url': None, 'download_url': 'UNKNOWN', 'downloads': {'last_day': -1, 'last_month': -1, 'last_week': -1}, 'home_page': 'https://github.com/pypa/sampleproject', 'keywords': 'sample setuptools development', 'license': 'MIT', 'maintainer': None, 'maintainer_email': None, 'name': 'sampleproject', 'package_url': 'https://pypi.org/project/sampleproject/', 'platform': 'UNKNOWN', 'project_url': 'https://pypi.org/project/sampleproject/', 'project_urls': {'Download': 'UNKNOWN',                  'Homepage': 'https://github.com/pypa/sampleproject'}, 'release_url': 'https://pypi.org/project/sampleproject/1.2.0/', 'requires_dist': None, 'requires_python': None, 'summary': 'A sample Python project', 'version': '1.2.0'}

The result can be limited to a certaindepth (ellipsis is used for deepercontents):

>>>pprint.pp(project_info,depth=1){'author': 'The Python Packaging Authority', 'author_email': 'pypa-dev@googlegroups.com', 'bugtrack_url': None, 'classifiers': [...], 'description': 'A sample Python project\n'                '=======================\n'                '\n'                'This is the description file for the project.\n'                '\n'                'The file should use UTF-8 encoding and be written using '                'ReStructured Text. It\n'                'will be used to generate the project webpage on PyPI, and '                'should be written for\n'                'that purpose.\n'                '\n'                'Typical contents for this file would include an overview of '                'the project, basic\n'                'usage examples, etc. Generally, including the project '                'changelog in here is not\n'                'a good idea, although a simple "What\'s New" section for the '                'most recent version\n'                'may be appropriate.', 'description_content_type': None, 'docs_url': None, 'download_url': 'UNKNOWN', 'downloads': {...}, 'home_page': 'https://github.com/pypa/sampleproject', 'keywords': 'sample setuptools development', 'license': 'MIT', 'maintainer': None, 'maintainer_email': None, 'name': 'sampleproject', 'package_url': 'https://pypi.org/project/sampleproject/', 'platform': 'UNKNOWN', 'project_url': 'https://pypi.org/project/sampleproject/', 'project_urls': {...}, 'release_url': 'https://pypi.org/project/sampleproject/1.2.0/', 'requires_dist': None, 'requires_python': None, 'summary': 'A sample Python project', 'version': '1.2.0'}

Additionally, maximum characterwidth can be suggested. If a long objectcannot be split, the specified width will be exceeded:

>>>pprint.pp(project_info,depth=1,width=60){'author': 'The Python Packaging Authority', 'author_email': 'pypa-dev@googlegroups.com', 'bugtrack_url': None, 'classifiers': [...], 'description': 'A sample Python project\n'                '=======================\n'                '\n'                'This is the description file for the '                'project.\n'                '\n'                'The file should use UTF-8 encoding and be '                'written using ReStructured Text. It\n'                'will be used to generate the project '                'webpage on PyPI, and should be written '                'for\n'                'that purpose.\n'                '\n'                'Typical contents for this file would '                'include an overview of the project, '                'basic\n'                'usage examples, etc. Generally, including '                'the project changelog in here is not\n'                'a good idea, although a simple "What\'s '                'New" section for the most recent version\n'                'may be appropriate.', 'description_content_type': None, 'docs_url': None, 'download_url': 'UNKNOWN', 'downloads': {...}, 'home_page': 'https://github.com/pypa/sampleproject', 'keywords': 'sample setuptools development', 'license': 'MIT', 'maintainer': None, 'maintainer_email': None, 'name': 'sampleproject', 'package_url': 'https://pypi.org/project/sampleproject/', 'platform': 'UNKNOWN', 'project_url': 'https://pypi.org/project/sampleproject/', 'project_urls': {...}, 'release_url': 'https://pypi.org/project/sampleproject/1.2.0/', 'requires_dist': None, 'requires_python': None, 'summary': 'A sample Python project', 'version': '1.2.0'}