我尝试使用pprint
库,但它的输出仅有一行,没有多行输出和缩进。
我使用namedtuple的_asdict
方法。
但它返回一个OrderedDict
,而pprint
不会缩进,所以我将其转换为一个dict
:
>>> from collections import namedtuple
>>> Busbar = namedtuple('Busbar', 'id name voltage')
>>> busbar = Busbar(id=102, name='FACTORY', voltage=21.8)
使用 pprint
和 dict
:
>>> from pprint import pprint
>>> pprint(dict(busbar._asdict()))
{'id': 102,
'name': 'FACTORY',
'voltage': 21.8}
vars
应用于命名元组会引发TypeError: vars() argument must have __dict__ attribute
错误。使用方法_as_dict
的早期版本可以解决此问题。 - 0 __as_dict
的答案版本。 - Peter WoodPython 3中的pprint PrettyPrinter比Python 2中使用的要更加可扩展。您可以创建自己的打印机,如下所示,以添加处理所需对象的方法,而无需过多地干扰pprint“私有”方法和属性。
您可以在此处查看在线示例:https://repl.it/HkDd/1
from io import StringIO
import pprint
class MyPrettyPrinter(pprint.PrettyPrinter):
def format_namedtuple(self, object, stream, indent, allowance, context, level):
# Code almost equal to _format_dict, see pprint code
write = stream.write
write(object.__class__.__name__ + '(')
object_dict = object._asdict()
length = len(object_dict)
if length:
# We first try to print inline, and if it is too large then we print it on multiple lines
inline_stream = StringIO()
self.format_namedtuple_items(object_dict.items(), inline_stream, indent, allowance + 1, context, level, inline=True)
max_width = self._width - indent - allowance
if len(inline_stream.getvalue()) > max_width:
self.format_namedtuple_items(object_dict.items(), stream, indent, allowance + 1, context, level, inline=False)
else:
stream.write(inline_stream.getvalue())
write(')')
def format_namedtuple_items(self, items, stream, indent, allowance, context, level, inline=False):
# Code almost equal to _format_dict_items, see pprint code
indent += self._indent_per_level
write = stream.write
last_index = len(items) - 1
if inline:
delimnl = ', '
else:
delimnl = ',\n' + ' ' * indent
write('\n' + ' ' * indent)
for i, (key, ent) in enumerate(items):
last = i == last_index
write(key + '=')
self._format(ent, stream, indent + len(key) + 2,
allowance if last else 1,
context, level)
if not last:
write(delimnl)
def _format(self, object, stream, indent, allowance, context, level):
# We dynamically add the types of our namedtuple and namedtuple like
# classes to the _dispatch object of pprint that maps classes to
# formatting methods
# We use a simple criteria (_asdict method) that allows us to use the
# same formatting on other classes but a more precise one is possible
if hasattr(object, '_asdict') and type(object).__repr__ not in self._dispatch:
self._dispatch[type(object).__repr__] = MyPrettyPrinter.format_namedtuple
super()._format(object, stream, indent, allowance, context, level)
然后像这样使用它:
from collections import namedtuple
Segment = namedtuple('Segment', 'p1 p2')
# Your own namedtuple-like class
class Node:
def __init__(self, x, y, segments=[]):
self.x = x
self.y = y
self.segments = segments
def _asdict(self):
return {"x": self.x, "y": self.y, "segments": self.segments}
# Default repr
def __repr__(self):
return "Node(x={}, y={}, segments={})".format(self.x, self.y, self.segments)
# A circular structure for the demo
node = Node(0, 0)
segments = [
Segment(node, Node(1, 1)),
Segment(node, Node(2, 1)),
Segment(node, Node(1, 2, segments=[
Segment(Node(2, 3), Node(1, 1)),
])),
]
node.segments = segments
pp = MyPrettyPrinter(indent=2, depth=2)
pp.pprint(node)
输出
Node(
x=0,
y=0,
segments=[ Segment(
p1=<Recursion on Node with id=139778851454536>,
p2=Node(x=1, y=1, segments=[])),
Segment(
p1=<Recursion on Node with id=139778851454536>,
p2=Node(x=2, y=1, segments=[])),
Segment(
p1=<Recursion on Node with id=139778851454536>,
p2=Node(x=1, y=2, segments=[...]))])
import black
# value_to_print can either be a namedtuple, or a container containing tuples,
# or a namedtuple containing containers containing other namedtuples,
# or whatever else you want.
print(black.format_str(repr(value_to_print), mode=black.Mode()))
这需要安装black,可以通过 pip install black
完成。
sudo
安装 Python 包 - 这可能会导致系统包出现问题并破坏任何虚拟环境。只需使用 pip install..
- 在很少的情况下(我想说没有,但可能有一些特殊情况),您需要使用 sudo pip install..
。 - Jan Spurny
__repr__
。 - jonrsharpe