如果不是为了美观的打印，那么该reprlib模块将成为解决问题的方法：它是为深度嵌套和递归/自引用数据结构的安全，优雅和可自定义的处理而设计的。
但是，事实证明，将reprlib和pprint模块组合起来并非易事，至少在不破坏某些漂亮印刷方面的前提下，我无法提出一种简洁的方法。
因此，这是一个解决方案，仅PrettyPrinter在需要时才将其分类为裁剪/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'], '...'],
'...']}
输出为maxlist=5（触发将列表分成几行）：
{'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',
'...']}
笔记：
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