打印 Python 的一切 —— pprint & beeprint

打印，是全部程序員從小白時期就具有的神技，遇事不決打印一下，是 DEBUG 最簡單且不依賴 IDE 的方式，自定義各類日誌輸出，也是項目成型後必備功能。
可是爲了優雅的打印格式，每每須要對各類對象進行特殊格式化，可遇到字典和大段字符串也很差處理。
這篇文章介紹兩個庫模塊，能夠快速有效的解決全部 Python 對象的打印輸出，沒錯，全部。

pprint

這是 Python 標準庫模塊，全稱 pretty printer，可讓各類數據結構更美觀地輸出。

>>> print(game)
{'players': [{'name': 'player_1', 'hp': 3}, {'name': 'player_2', 'hp': 5}]}
>>> pprint.pprint(game, width=4)
{'players': [{'hp': 3,
              'name': 'player_1'},
             {'hp': 5,
              'name': 'player_2'}]}

 

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

• stream：輸出流，默認是 sys.stdout ，也就是屏幕輸出。
• indent：縮進空格數。
• width：每行最大寬度，默認爲80個字符，超過寬度會換行，但若是單個對象超過不會被換行，好比一段長字符串。
• depth：限制數據的層級，設置後能夠限制過多的嵌套。
• compact：3.4版本新加入的參數，若設爲 True ，則輸出會在接近 width 限制才進行換行。

>>> pprint.pprint(stuff, indent=4)
[   ['spam', 'eggs', 'lumberjack', 'knights', 'ni'],
    'spam',
    'eggs',
    'lumberjack',
    'knights',
    'ni']
>>> pprint.pprint(stuff, width=41, compact=True)
[['spam', 'eggs', 'lumberjack',
  'knights', 'ni'],
 'spam', 'eggs', 'lumberjack', 'knights',
 'ni']

 

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

和 pprint.pprint 的區別是，該函數不會打印到輸出流，而是返回一個格式化字符串。

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

 

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

上文兩個函數，實際都是構建一個 PrettyPrinter 對象，並調用對應的方法，因此當須要複用格式化的時候，咱們能夠提早構建該對象。

>>> pp = pprint.PrettyPrinter(width=40, compact=True)
>>> pp.pprint(game)
{'players': [{'hp': 3,
              'name': 'player_1'},
             {'hp': 5,
              'name': 'player_2'}]}
>>> pp.pprint(stuff)
['spam', 'eggs', 'lumberjack',
 'knights', 'ni']

 

更多用法能夠參考官方文檔：

8.11. pprint - Data pretty printer - Python 3.5.6 documentation​docs.python.org

 

---

pprint 對字典 列表這類數據結構確實很好用，但遇到類、字符串仍然和 print 差異不大，所以這裏有一個國人寫的第三方庫介紹給你們。

beeprint

除了和 pprint 同樣支持 dict, list, tuple 等常規變量的格式化輸出，還支持 object 變量打印、長文本自動剪切。

下面是做者 README 中和 pprint 的對比：

pprint:

{'entities': {'hashtags': [],
              'urls': [{'display_url': 'tumblr.com/xnr37hf0yz',
                        'expanded_url': 'http://tumblr.com/xnr37hf0yz',
                        'indices': [107, 126],
                        'url': 'http://t.co/cCIWIwg'}],
              'user_mentions': []}}

beeprint:

{
  'entities': {
    'hashtags': [],
    'urls': [
      {
        'display_url': 'tumblr.com/xnr37hf0yz',
        'expanded_url': 'http://tumblr.com/xnr37hf0yz',
        'indices': [107, 126],
        'url': 'http://t.co/cCIWIwg',
      },
    ],
    'user_mentions': [],
  },
}

 

pprint:

<class 'definition.NormalClassNewStyle'>

beeprint:

class(NormalClassNewStyle):
  dicts: {
  },
  lists: [],
  static_props: 1,
  tuple: (1, 2)

 

pprint:

<definition.NormalClassNewStyle object at 0x7f338e5a9dd0>

beeprint:

instance(NormalClassNewStyle):
  dicts: {
  },
  lists: [],
  say_hi: 'hello world',
  static_props: 1,
  tuple: (1, 2)

 

pprint:

[['\nThe sky and the earth were at first one blurred entity like an egg. Pangu was born into it.\n \n\tThe separation of the sky and the earth took eighteen thousand years-the yang which was light and pure rose to become the sky, \tand the yin which was heavy and murky\xef\xbc\x88\xe6\x9c\xa6\xe8\x83\xa7\xe7\x9a\x84\xef\xbc\x89 sank to form the earth. Between them was Pangu, who went through nine \tchanges every day, his wisdom greater than that of the sky and his ability greater than that of the earth. Every day the sky rose ten feet higher, the earth became ten feet thicker, and Pangu grew ten feet taller.\n \nAnother eighteen thousand years passed, and there was an extremely high sky, an extremely thick earth, and an extremely tall Pangu. After Pangu died, his head turned into the Five Sacred Mountains (Mount Tai, Mount Heng, Mount Hua, Mount Heng, Mount Song), his eyes turned into the moon and the sun, his blood changed into water in river and sea, his hair into grass.\n \nIn all, the universe and Pangu combine in one.\n',
  '\n\xe6\x8d\xae\xe6\xb0\x91\xe9\x97\xb4\xe7\xa5\x9e\xe8\xaf\x9d\xe4\xbc\xa0\xe8\xaf\xb4\xe5\x8f\xa4\xe6\x97\xb6\xe7\x9b\x98\xe5\x8f\xa4\xe7\x94\x9f\xe5\x9c\xa8\xe9\xbb\x91\xe6\x9a\x97\xe5\x9b\xa2\xe4\xb8\xad\xef\xbc\x8c\xe4\xbb\x96\xe4\xb8\x8d\xe8\x83\xbd\xe5\xbf\x8d\xe5\x8f\x97\xe9\xbb\x91\xe6\x9a\x97\xef\xbc\x8c\xe7\x94\xa8\xe7\xa5\x9e\xe6\x96\xa7\xe5\x8a\x88\xe5\x90\x91\xe5\x9b\x9b\xe6\x96\xb9\xef\xbc\x8c\xe9\x80\x90\xe6\xb8\x90\xe4\xbd\xbf\xe5\xa4\xa9\xe7\xa9\xba\xe9\xab\x98\xe8\xbf\x9c\xef\xbc\x8c\xe5\xa4\xa7\xe5\x9c\xb0\xe8\xbe\xbd\xe9\x98\x94\xe3\x80\x82\n\t\xe4\xbb\x96\xe4\xb8\xba\xe4\xb8\x8d\xe4\xbd\xbf\xe5\xa4\xa9\xe5\x9c\xb0\xe4\xbc\x9a\xe9\x87\x8d\xe6\x96\xb0\xe5\x90\x88\xe5\xb9\xb6\xef\xbc\x8c\xe7\xbb\xa7\xe7\xbb\xad\xe6\x96\xbd\xe5\xb1\x95\xe6\xb3\x95\xe6\x9c\xaf\xe3\x80\x82\xe6\xaf\x8f\xe5\xbd\x93\xe7\x9b\x98\xe5\x8f\xa4\xe7\x9a\x84\xe8\xba\xab\xe4\xbd\x93\xe9\x95\xbf\xe9\xab\x98\xe4\xb8\x80\xe5\xb0\xba\xef\xbc\x8c\xe5\xa4\xa9\xe7\xa9\xba\xe5\xb0\xb1\xe9\x9a\x8f\xe4\xb9\x8b\xe5\xa2\x9e\xe9\xab\x98\xe4\xb8\x80\xe5\xb0\xba\xef\xbc\x8c\n\t\xe7\xbb\x8f\xe8\xbf\x871.8\xe4\xb8\x87\xe5\xa4\x9a\xe5\xb9\xb4\xe7\x9a\x84\xe5\x8a\xaa\xe5\x8a\x9b\xef\xbc\x8c\xe7\x9b\x98\xe5\x8f\xa4\xe5\x8f\x98\xe6\x88\x90\xe4\xb8\x80\xe4\xbd\x8d\xe9\xa1\xb6\xe5\xa4\xa9\xe7\xab\x8b\xe5\x9c\xb0\xe7\x9a\x84\xe5\xb7\xa8\xe4\xba\xba\xef\xbc\x8c\xe8\x80\x8c\xe5\xa4\xa9\xe7\xa9\xba\xe4\xb9\x9f\xe5\x8d\x87\xe5\xbe\x97\xe9\xab\x98\xe4\xb8\x8d\xe5\x8f\xaf\xe5\x8f\x8a\xef\xbc\x8c\xe5\xa4\xa7\xe5\x9c\xb0\xe4\xb9\x9f\xe5\x8f\x98\xe5\xbe\x97\xe5\x8e\x9a\xe5\xae\x9e\xe6\x97\xa0\xe6\xaf\x94\xe3\x80\x82\xe7\x9b\x98\xe5\x8f\xa4\xe7\x94\x9f\xe5\x89\x8d\xe5\xae\x8c\xe6\x88\x90\xe5\xbc\x80\xe5\xa4\xa9\xe8\xbe\x9f\xe5\x9c\xb0\xe7\x9a\x84\xe4\xbc\x9f\xe5\xa4\xa7\xe4\xb8\x9a\xe7\xbb\xa9\xef\xbc\x8c\xe6\xad\xbb\xe5\x90\x8e\xe6\xb0\xb8\xe8\xbf\x9c\xe7\x95\x99\xe7\xbb\x99\xe5\x90\x8e\xe4\xba\xba\xe6\x97\xa0\xe7\xa9\xb7\xe6\x97\xa0\xe5\xb0\xbd\xe7\x9a\x84\xe5\xae\x9d\xe8\x97\x8f\xef\xbc\x8c\xe6\x88\x90\xe4\xb8\xba\xe4\xb8\xad\xe5\x8d\x8e\xe6\xb0\x91\xe6\x97\x8f\xe5\xb4\x87\xe6\x8b\x9c\xe7\x9a\x84\xe8\x8b\xb1\xe9\x9b\x84\xe3\x80\x82\n']]

beeprint:

[
  [
    '\nThe sky and the earth were at first one blurred entity like an egg. Pangu
     was born into it.\n \n\tThe separation of the sky and the earth took
     ...(12 hidden lines)',
    '\n據民間神話傳說古時盤古生在黑暗團中，他不能忍受黑暗，用神斧劈向四方，逐漸
     使天空高遠，大地遼闊。\n\t他爲不使天地會從新合併，繼續施展法術。每當盤古的
     ...(3 hidden lines)',
  ],
]

 

beeprint.pp(o, output=True, max_depth=5, indent=2, width=80, sort_keys=True, config=None, **kwargs):

參數和 pprint 相似，多出了 sort_keys能夠打印字典時是否按 key 排序（ pprint 是默認排序，不可選），另外還有控制文本裁剪等行爲的參數，能夠從 beeprint.Config 裏查看。

 

該庫的 Github：https://github.com/panyanyany/beeprint

 

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