"pprint" --- Data pretty printer#

Código fuente: Lib/pprint.py

======================================================================

The "pprint" module provides a capability to "pretty-print" arbitrary Python data structures in a form which can be used as input to the interpreter. If the formatted structures include objects which are not fundamental Python types, the representation may not be loadable. This may be the case if objects such as files, sockets or classes are included, as well as many other objects which are not representable as Python literals.

The formatted representation keeps objects on a single line if it can, and breaks them onto multiple lines if they don't fit within the allowed width, adjustable by the width parameter defaulting to 80 characters.

Distinto en la versión 3.9: Soporte añadido para imprimir de forma bonita "types.SimpleNamespace".

Distinto en la versión 3.10: Soporte añadido para imprimir de forma bonita "dataclasses.dataclass".

Functions#

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

Prints the formatted representation of object, followed by a newline. This function may be used in the interactive interpreter instead of the "print()" function for inspecting values. Tip: you can reassign "print = pprint.pp" for use within a scope.

Parámetros: * object -- The object to be printed.

  * **stream** (*file-like object* | None) -- A file-like object
    to which the output will be written by calling its "write()"
    method. If "None" (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 "...". If
    "None" (the default), there is no constraint on the depth of
    the objects being formatted.

  * **compact** (*bool*) -- Control the way long *sequences* are
    formatted. If "False" (the default), each item of a sequence
    will be formatted on a separate line, otherwise as many items
    as will fit within the *width* will be formatted on each
    output line.

  * **sort_dicts** (*bool*) -- If "True", dictionaries will be
    formatted with their keys sorted, otherwise they will be
    displayed in insertion order (the default).

  * **underscore_numbers** (*bool*) -- If "True", integers will be
    formatted with the "_" character for a thousands separator,
    otherwise underscores are not displayed (the default).

import pprint stuff = ['spam', 'eggs', 'lumberjack', 'knights', 'ni'] stuff.insert(0, stuff) pprint.pp(stuff) [, 'spam', 'eggs', 'lumberjack', 'knights', 'ni']

Added in version 3.8.

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

Alias for "pp()" with sort_dicts set to "True" by default, which would automatically sort the dictionaries' keys, you might want to use "pp()" instead where it is "False" by default.

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

Return the formatted representation of object as a string. indent, width, depth, compact, sort_dicts and underscore_numbers are passed to the "PrettyPrinter" constructor as formatting parameters and their meanings are as described in the documentation above.

pprint.isreadable(object)

Determina si la representación formateada de object es "legible" o si puede usarse para reconstruir el objeto usando "eval()". Siempre retorna "False" para objetos recursivos.

pprint.isreadable(stuff) False

pprint.isrecursive(object)

Determine if object requires a recursive representation. This function is subject to the same limitations as noted in "saferepr()" below and may raise an "RecursionError" if it fails to detect a recursive object.

pprint.saferepr(object)

Return a string representation of object, protected against recursion in some common data structures, namely instances of "dict", "list" and "tuple" or subclasses whose "repr" has not been overridden. If the representation of object exposes a recursive entry, the recursive reference will be represented as "". The representation is not otherwise formatted.

pprint.saferepr(stuff) "[, 'spam', 'eggs', 'lumberjack', 'knights', 'ni']"

Objetos PrettyPrinter#

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

Construct a "PrettyPrinter" instance.

Arguments have the same meaning as for "pp()". Note that they are in a different order, and that sort_dicts defaults to "True".

import pprint 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', (...)))))))

Distinto en la versión 3.4: Añadido el argumento compact.

Distinto en la versión 3.8: Añadido el argumento sort_dicts.

Distinto en la versión 3.10: Se agregó el parámetro underscore_numbers.

Distinto en la versión 3.11: No longer attempts to write to "sys.stdout" if it is "None".

Las instancias de "PrettyPrinter" tienen los siguientes métodos:

PrettyPrinter.pformat(object)

Retorna la representación formateada de object. Tiene en cuenta las opciones pasadas al constructor de la clase "PrettyPrinter".

PrettyPrinter.pprint(object)

Imprime la representación formateada de object en la secuencia configurada, seguida de una nueva línea.

Los siguientes métodos proporcionan las implementaciones para las funciones correspondientes con los mismos nombres. Usar estos métodos en una instancia es algo más eficiente, ya que no es necesario crear nuevos objetos "PrettyPrinter".

PrettyPrinter.isreadable(object)

Determina si la representación formateada de object es "legible" o si se puede usar para reconstruir su valor usando "eval()". Se debe tener en cuenta que se retorna "False" para objetos recursivos. Si el parámetro depth de "PrettyPrinter" es proporcionado y el objeto es más profundo de lo permitido, también se retorna "False".

PrettyPrinter.isrecursive(object)

Determina si object requiere una representación recursiva.

Este método se proporciona como un punto de entrada o método de enlace automático (hook en inglés) para permitir que las subclases modifiquen la forma en que los objetos se convierten en cadenas de caracteres. La implementación por defecto utiliza la implementación interna de "saferepr()".

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

Retorna tres valores: la versión formateada de object como una cadena de caracteres, una bandera que indica si el resultado es legible y una bandera que indica si se detectó recursividad. El primer argumento es el objeto a representar. El segundo es un diccionario que contiene la "id()" de los objetos que son parte del contexto de representación actual (contenedores directos e indirectos para object que están afectando a la representación), como las claves; si es necesario representar un objeto que ya está representado en context, el tercer valor de retorno será "True". Las llamadas recursivas al método "format()" deben agregar entradas adicionales a los contenedores de este diccionario. El tercer argumento, maxlevels, proporciona el límite máximo de recursividad; su valor por defecto es "0". Este argumento debe pasarse sin modificaciones a las llamadas recursivas. El cuarto argumento, level, da el nivel actual; las llamadas recursivas sucesivas deben pasar un valor menor que el de la llamada actual.

Ejemplo#

To demonstrate several uses of the "pp()" function and its parameters, let's fetch information about a project from PyPI:

import json import pprint from urllib.request import urlopen with urlopen('https://pypi.org/pypi/sampleproject/1.2.0/json') as resp: ... 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'}

El resultado puede limitarse a una cierta profundidad asignando un valor al argumento depth ("..." se utiliza para contenidos más "profundos"):

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'}

Además, se puede establecer un valor máximo de caracteres por línea asignando un valor al parámetro width. Si un objeto largo no se puede dividir, el valor dado al ancho se anulará y será excedido:

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'}