python之pprint模块简用

时间：2022-12-04 18:09:49

pprint module提供了可以按照某个格式正确的显示python已知类型数据的一种方法，这种格式可被解析器解析, 又很易读。但是，如果已知格式的数据对象不是python的基础类型，这种表示方法就有可能加载失败。这种情况一般是对象为 files, sockets, classes, or instances are included, as well as many other built-in objects which are not representable as Python constants。

该方法输出将对象的输出分隔成单行显示，并在宽度设置不适合时，将其分成多行显示。

class pprint.PrettyPrinter(indent=1,width=80,depth=None,stream=None)

pprint. pformat ( object, indent=1, width=80, depth=None )仅仅想获得数据而不是输出数据也可以用pformat

Return the formatted representation of object as a string. indent,widthanddepth will be passed to thePrettyPrinter constructor as formatting parameters.

pprint. pprint ( object, stream=None, indent=1, width=80, depth=None )

Prints the formatted representation of object on stream, followed by anewline.

pprint. isreadable ( object )

Determine if the formatted representation of object is “readable,” or can be used to reconstruct the value usingeval(). This always returnsFalse for recursive objects.

>>> import sys
>>> import pprint
>>> pprint.pprint(sys.path)
['D:/Python/tmp',
 'D:\\Python\\tmp',
 'C:\\Python27\\Lib\\idlelib',
 'C:\\Python27\\lib\\site-packages\\zope.interface-4.0.0-py2.7-win32.egg',
 'C:\\Python27\\lib\\site-packages\\pyopenssl-0.13-py2.7-win32.egg',
 'C:\\Python27\\lib\\site-packages\\scrapy-0.14.4-py2.7.egg',
 'C:\\Python27\\lib\\site-packages\\w3lib-1.2-py2.7.egg',
 'C:\\Python27\\lib\\site-packages\\mysql_python-1.2.3-py2.7-win32.egg',
 'C:\\Python27\\lib\\site-packages\\paramiko-1.9.0-py2.7.egg',
 'C:\\Python27\\lib\\site-packages\\pycrypto-2.6-py2.7-win32.egg',
 'C:\\Python27\\lib\\site-packages\\requests-2.0.0-py2.7.egg',
 'C:\\Python27\\lib\\site-packages\\reportlab-2.7-py2.7-win32.egg',
 'C:\\Windows\\system32\\python27.zip',
 'C:\\Python27\\DLLs',
 'C:\\Python27\\lib',
 'C:\\Python27\\lib\\plat-win',
 'C:\\Python27\\lib\\lib-tk',
 'C:\\Python27',
 'C:\\Python27\\lib\\site-packages',
 'C:\\Python27\\lib\\site-packages\\wx-2.8-msw-unicode']
>>> print sys.path #一行显示，显示很长
['D:/Python/tmp', 'D:\\Python\\tmp', 'C:\\Python27\\Lib\\idlelib', 'C:\\Python27\\lib\\site-packages\\zope.interface-4.0.0-py2.7-win32.egg', 'C:\\Python27\\lib\\site-packages\\pyopenssl-0.13-py2.7-win32.egg', 'C:\\Python27\\lib\\site-packages\\scrapy-0.14.4-py2.7.egg', 'C:\\Python27\\lib\\site-packages\\w3lib-1.2-py2.7.egg', 'C:\\Python27\\lib\\site-packages\\mysql_python-1.2.3-py2.7-win32.egg', 'C:\\Python27\\lib\\site-packages\\paramiko-1.9.0-py2.7.egg', 'C:\\Python27\\lib\\site-packages\\pycrypto-2.6-py2.7-win32.egg', 'C:\\Python27\\lib\\site-packages\\requests-2.0.0-py2.7.egg', 'C:\\Python27\\lib\\site-packages\\reportlab-2.7-py2.7-win32.egg', 'C:\\Windows\\system32\\python27.zip', 'C:\\Python27\\DLLs', 'C:\\Python27\\lib', 'C:\\Python27\\lib\\plat-win', 'C:\\Python27\\lib\\lib-tk', 'C:\\Python27', 'C:\\Python27\\lib\\site-packages', 'C:\\Python27\\lib\\site-packages\\wx-2.8-msw-unicode']
>>> string = pprint.pformat(sys.path)
>>> string #还是一行
"['D:/Python/tmp',\n 'D:\\\\Python\\\\tmp',\n 'C:\\\\Python27\\\\Lib\\\\idlelib',\n 'C:\\\\Python27\\\\lib\\\\site-packages\\\\zope.interface-4.0.0-py2.7-win32.egg',\n 'C:\\\\Python27\\\\lib\\\\site-packages\\\\pyopenssl-0.13-py2.7-win32.egg',\n 'C:\\\\Python27\\\\lib\\\\site-packages\\\\scrapy-0.14.4-py2.7.egg',\n 'C:\\\\Python27\\\\lib\\\\site-packages\\\\w3lib-1.2-py2.7.egg',\n 'C:\\\\Python27\\\\lib\\\\site-packages\\\\mysql_python-1.2.3-py2.7-win32.egg',\n 'C:\\\\Python27\\\\lib\\\\site-packages\\\\paramiko-1.9.0-py2.7.egg',\n 'C:\\\\Python27\\\\lib\\\\site-packages\\\\pycrypto-2.6-py2.7-win32.egg',\n 'C:\\\\Python27\\\\lib\\\\site-packages\\\\requests-2.0.0-py2.7.egg',\n 'C:\\\\Python27\\\\lib\\\\site-packages\\\\reportlab-2.7-py2.7-win32.egg',\n 'C:\\\\Windows\\\\system32\\\\python27.zip',\n 'C:\\\\Python27\\\\DLLs',\n 'C:\\\\Python27\\\\lib',\n 'C:\\\\Python27\\\\lib\\\\plat-win',\n 'C:\\\\Python27\\\\lib\\\\lib-tk',\n 'C:\\\\Python27',\n 'C:\\\\Python27\\\\lib\\\\site-packages',\n 'C:\\\\Python27\\\\lib\\\\site-packages\\\\wx-2.8-msw-unicode']"
>>> print string #输出格式变成了单行
['D:/Python/tmp',
 'D:\\Python\\tmp',
 'C:\\Python27\\Lib\\idlelib',
 'C:\\Python27\\lib\\site-packages\\zope.interface-4.0.0-py2.7-win32.egg',
 'C:\\Python27\\lib\\site-packages\\pyopenssl-0.13-py2.7-win32.egg',
 'C:\\Python27\\lib\\site-packages\\scrapy-0.14.4-py2.7.egg',
 'C:\\Python27\\lib\\site-packages\\w3lib-1.2-py2.7.egg',
 'C:\\Python27\\lib\\site-packages\\mysql_python-1.2.3-py2.7-win32.egg',
 'C:\\Python27\\lib\\site-packages\\paramiko-1.9.0-py2.7.egg',
 'C:\\Python27\\lib\\site-packages\\pycrypto-2.6-py2.7-win32.egg',
 'C:\\Python27\\lib\\site-packages\\requests-2.0.0-py2.7.egg',
 'C:\\Python27\\lib\\site-packages\\reportlab-2.7-py2.7-win32.egg',
 'C:\\Windows\\system32\\python27.zip',
 'C:\\Python27\\DLLs',
 'C:\\Python27\\lib',
 'C:\\Python27\\lib\\plat-win',
 'C:\\Python27\\lib\\lib-tk',
 'C:\\Python27',
 'C:\\Python27\\lib\\site-packages',
 'C:\\Python27\\lib\\site-packages\\wx-2.8-msw-unicode']
>>> 

>>> stuff = ['spam','eggs','lumberjack','knight','ni']>>> pprint.pprint(stuff)
['spam', 'eggs', 'lumberjack', 'knight', 'ni']
>>> print stuff
['spam', 'eggs', 'lumberjack', 'knight', 'ni']
>>> stuff.insert(0,stuff)
>>> pprint.pprint(stuff)#If stream is None, sys.stdout is used.  This may be used in the interactive interpreter instead of a print statement
# for inspecting values.
[<Recursion on list with id=33573024>,
 'spam',
 'eggs',
 'lumberjack',
 'knight',
 'ni']
>>> print stuff
[[...], 'spam', 'eggs', 'lumberjack', 'knight', 'ni']
>>> 
>>> pprint.isreadable(stuff)#Determine if the formatted representation of object is “readable“
False
>>> pprint.isreadable(sys.path)
True
>>>

# This example demonstrates several uses of the pprint() function and its parameters.

如下例，依次为：


#list中包含tuple
#按照指定深度来显示stuff内容
#The number of levels which may be printed is controlled by depth; if the data structure being printed is too deep, the next contained level is replaced by ....
#The desired output width is constrained using the width parameter; the default is 80 characters.

If a structure cannot be formatted within the constrained width, a best effort will be made.

>>> tup = ('spam',('eggs',('lumberjack',)))
>>> stuff = ['a'*5, tup, ['b'*5, 'c'*5],['c'*5, 'd'*5]]
>>> stuff
['aaaaa', ('spam', ('eggs', ('lumberjack',))), ['bbbbb', 'ccccc'], ['ccccc', 'ddddd']]
>>> pprint.pprint(stuff)
['aaaaa',
 ('spam', ('eggs', ('lumberjack',))),
 ['bbbbb', 'ccccc'],
 ['ccccc', 'ddddd']]
>>> pprint.pprint(stuff,depth=3)
['aaaaa', ('spam', ('eggs', (...,))), ['bbbbb', 'ccccc'], ['ccccc', 'ddddd']]
>>> pprint.pprint(stuff,depth=4)
['aaaaa',
 ('spam', ('eggs', ('lumberjack',))),
 ['bbbbb', 'ccccc'],
 ['ccccc', 'ddddd']]
>>> pprint.pprint(stuff,depth=2)
['aaaaa', ('spam', (...)), ['bbbbb', 'ccccc'], ['ccccc', 'ddddd']]
>>> pprint.pprint(stuff,width=40)
['aaaaa',
 ('spam', ('eggs', ('lumberjack',))),
 ['bbbbb', 'ccccc'],
 ['ccccc', 'ddddd']]
>>> pprint.pprint(stuff,width=80)
['aaaaa',
 ('spam', ('eggs', ('lumberjack',))),
 ['bbbbb', 'ccccc'],
 ['ccccc', 'ddddd']]
>>> pprint.pprint(stuff,width=3)
['aaaaa',
 ('spam',
  ('eggs',
   ('lumberjack',))),
 ['bbbbb',
  'ccccc'],
 ['ccccc',
  'ddddd']]
>>>







总的来说，感觉目前用处不是很大，没有什么特别的地方，就是对输出的一种格式化。





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