Python 漂亮的列表字典，缩写长列表

Question

我有一本列表字典，列表很长。如何以仅显示列表中的几个元素的方式打印它？显然，我可以为此编写一个自定义函数，但是否有任何内置方法或库可以实现这一点？例如，当打印大型数据帧时，pandas 可以用很短的方式很好地打印它。

这个例子更好地说明了我的意思：

obj = {'key_1': ['EG8XYD9FVN',
  'S2WARDCVAO',
  'J00YCU55DP',
  'R07BUIF2F7',
  'VGPS1JD0UM',
  'WL3TWSDP8E',
  'LD8QY7DMJ3',
  'J36U3Z9KOQ',
  'KU2FUGYB2U',
  'JF3RQ315BY'],
 'key_2': ['162LO154PM',
  '3ROAV881V2',
  'I4T79LP18J',
  'WBD36EM6QL',
  'DEIODVQU46',
  'KWSJA5WDKQ',
  'WX9SVRFO0G',
  '6UN63WU64G',
  '3Z89U7XM60',
  '167CYON6YN']}

期望的输出：像这样：

{'key_1':
    ['EG8XYD9FVN', 'S2WARDCVAO', '...'],
 'key_2':
    ['162LO154PM', '3ROAV881V2', '...']
}

Answer 1

我写的这个递归函数可以满足你的要求。你也可以选择你想要的缩进

def pretty(d, indent=0):
    for key in sorted(d.keys()):
        print '\t' * indent + str(key)
        if isinstance(d[key], dict):
            pretty(d[key], indent+1)
        else:
            print '\t' * (indent+1) + str(d[key])

你的字典的输出是：

key_1
    ['EG8XYD9FVN', 'S2WARDCVAO', 'J00YCU55DP', 'R07BUIF2F7', 'VGPS1JD0UM', 'WL3TWSDP8E', 'LD8QY7DMJ3', 'J36U3Z9KOQ', 'KU2FUGYB2U', 'JF3RQ315BY']
key_2
    ['162LO154PM', '3ROAV881V2', 'I4T79LP18J', 'WBD36EM6QL', 'DEIODVQU46', 'KWSJA5WDKQ', 'WX9SVRFO0G', '6UN63WU64G', '3Z89U7XM60', '167CYON6YN']

Answer 2

您可以使用 pprint 模块：

pprint.pprint(obj)

会输出：

{'key_1': ['EG8XYD9FVN',
           'S2WARDCVAO',
           'J00YCU55DP',
           'R07BUIF2F7',
           'VGPS1JD0UM',
           'WL3TWSDP8E',
           'LD8QY7DMJ3',
           'J36U3Z9KOQ',
           'KU2FUGYB2U',
           'JF3RQ315BY'],
 'key_2': ['162LO154PM',
           '3ROAV881V2',
           'I4T79LP18J',
           'WBD36EM6QL',
           'DEIODVQU46',
           'KWSJA5WDKQ',
           'WX9SVRFO0G',
           '6UN63WU64G',
           '3Z89U7XM60',
           '167CYON6YN']}

而且，

pprint.pprint(obj,depth=1)

会输出：

{'key_1': [...], 'key_2': [...]}

并且，

pprint.pprint(obj,compact=True)

会输出：

{'key_1': ['EG8XYD9FVN', 'S2WARDCVAO', 'J00YCU55DP', 'R07BUIF2F7',
           'VGPS1JD0UM', 'WL3TWSDP8E', 'LD8QY7DMJ3', 'J36U3Z9KOQ',
           'KU2FUGYB2U', 'JF3RQ315BY'],
 'key_2': ['162LO154PM', '3ROAV881V2', 'I4T79LP18J', 'WBD36EM6QL',
           'DEIODVQU46', 'KWSJA5WDKQ', 'WX9SVRFO0G', '6UN63WU64G',
           '3Z89U7XM60', '167CYON6YN']}

Answer 3

使用reprlib。格式不是那么漂亮，但实际上是缩写。

> import repr
> repr.repr(map(lambda _: range(100000), range(10)))
'[[0, 1, 2, 3, 4, 5, ...], [0, 1, 2, 3, 4, 5, ...], [0, 1, 2, 3, 4, 5, ...], [0, 1, 2, 3, 4, 5, ...], [0, 1, 2, 3, 4, 5, ...], [0, 1, 2, 3, 4, 5, ...], ...]'
> repr.repr(dict(map(lambda i: (i, range(100000)), range(10))))
'{0: [0, 1, 2, 3, 4, 5, ...], 1: [0, 1, 2, 3, 4, 5, ...], 2: [0, 1, 2, 3, 4, 5, ...], 3: [0, 1, 2, 3, 4, 5, ...], ...}'

Answer 4

If it were not for the pretty printing, the reprlib module would be the way: Safe, elegant and customizable handling of deeply nested and recursive / self-referencing data structures is what it has what.

然而，事实证明将 reprlib 和 pprint 模块结合起来并不是微不足道的，至少我无法想出一个干净的在不破坏（某些）漂亮印刷方面的方式。

因此，这里有一个解决方案，只需 classes PrettyPrinter 根据需要裁剪/缩写列表：

from pprint import PrettyPrinter


obj = {
    'key_1': [
        'EG8XYD9FVN', 'S2WARDCVAO', 'J00YCU55DP', 'R07BUIF2F7', 'VGPS1JD0UM',
        'WL3TWSDP8E', 'LD8QY7DMJ3', 'J36U3Z9KOQ', 'KU2FUGYB2U', 'JF3RQ315BY',
    ],
    'key_2': [
        '162LO154PM', '3ROAV881V2', 'I4T79LP18J', 'WBD36EM6QL', 'DEIODVQU46',
        'KWSJA5WDKQ', 'WX9SVRFO0G', '6UN63WU64G', '3Z89U7XM60', '167CYON6YN',
    ],
    # Test case to make sure we didn't break handling of recursive structures
    'key_3': [
        '162LO154PM', '3ROAV881V2', [1, 2, ['a', 'b', 'c'], 3, 4, 5, 6, 7],
        'KWSJA5WDKQ', 'WX9SVRFO0G', '6UN63WU64G', '3Z89U7XM60', '167CYON6YN',
    ]
}


class CroppingPrettyPrinter(PrettyPrinter):

    def __init__(self, *args, **kwargs):
        self.maxlist = kwargs.pop('maxlist', 6)
        return PrettyPrinter.__init__(self, *args, **kwargs)

    def _format(self, obj, stream, indent, allowance, context, level):
        if isinstance(obj, list):
            # If object is a list, crop a copy of it according to self.maxlist
            # and append an ellipsis
            if len(obj) > self.maxlist:
                cropped_obj = obj[:self.maxlist] + ['...']
                return PrettyPrinter._format(
                    self, cropped_obj, stream, indent,
                    allowance, context, level)

        # Let the original implementation handle anything else
        # Note: No use of super() because PrettyPrinter is an old-style class
        return PrettyPrinter._format(
            self, obj, stream, indent, allowance, context, level)


p = CroppingPrettyPrinter(maxlist=3)
p.pprint(obj)

输出 maxlist=3:

{'key_1': ['EG8XYD9FVN', 'S2WARDCVAO', 'J00YCU55DP', '...'],
 'key_2': ['162LO154PM',
           '3ROAV881V2',
           [1, 2, ['a', 'b', 'c'], '...'],
           '...']}

使用 maxlist=5 的输出（触发在不同行上拆分列表）：

{'key_1': ['EG8XYD9FVN',
           'S2WARDCVAO',
           'J00YCU55DP',
           'R07BUIF2F7',
           'VGPS1JD0UM',
           '...'],
 'key_2': ['162LO154PM',
           '3ROAV881V2',
           'I4T79LP18J',
           'WBD36EM6QL',
           'DEIODVQU46',
           '...'],
 'key_3': ['162LO154PM',
           '3ROAV881V2',
           [1, 2, ['a', 'b', 'c'], 3, 4, '...'],
           'KWSJA5WDKQ',
           'WX9SVRFO0G',
           '...']}

备注：

这将创建份个列表。根据数据结构的大小，这在内存使用方面可能非常昂贵。
这只处理 lists 的特殊情况。必须为字典、元组、集合、frozensets 等实现等效行为，才能使 class 具有通用性。

Answer 5

你可以使用 IPython.lib.pretty.

from IPython.lib.pretty import pprint

> pprint(obj, max_seq_length=5)
{'key_1': ['EG8XYD9FVN',
  'S2WARDCVAO',
  'J00YCU55DP',
  'R07BUIF2F7',
  'VGPS1JD0UM',
  ...],
 'key_2': ['162LO154PM',
  '3ROAV881V2',
  'I4T79LP18J',
  'WBD36EM6QL',
  'DEIODVQU46',
  ...]}

> pprint(dict(map(lambda i: (i, range(i + 5)), range(100))), max_seq_length=10)
{0: [0, 1, 2, 3, 4],
 1: [0, 1, 2, 3, 4, 5],
 2: [0, 1, 2, 3, 4, 5, 6],
 3: [0, 1, 2, 3, 4, 5, 6, 7],
 4: [0, 1, 2, 3, 4, 5, 6, 7, 8],
 5: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9],
 6: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, ...],
 7: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, ...],
 8: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, ...],
 9: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, ...],
 ...}

对于旧版本的 IPython，您可以利用 RepresentationPrinter:

from IPython.lib.pretty import RepresentationPrinter
import sys

def compact_pprint(obj, max_seq_length=10):
    printer = RepresentationPrinter(sys.stdout)
    printer.max_seq_length = max_seq_length
    printer.pretty(obj)
    printer.flush()

Python 漂亮的列表字典，缩写长列表

Python pretty print dictionary of lists, abbreviate long lists

python

list

dictionary

pretty-print