Question

{'a': [{'c','d'},  {'d'}        ],
'b': [{'c','d'},  set()        ],
'c': [set(),      {'a','b','d'}],
'd': [{'a','c'},  {'a','b'}    ],
'e': [set(),      set()        ]}


class Graph:
    def __init__(self,*args):
        self.edges = {} 

    def __delitem__(self,item):
        if type(item) == tuple:
            for key,value in self.edges.items():
                if key == item[0] and item[1] in value[0]:
                    self.edges[item[0]].remove(item(1))
        elif item in self.edges.keys():
            del self.edges[item]
            for value in self.edges.values():
                if item in value:
                    value.remove(item)
        raise GraphError

delitem需要一个元组或一个str：

如果item参数是2元组，指定两者都在Graph中的原始节点和目标节点，则从Graph中删除该边。如果存在边缘，则更新原始节点和目标节点的集合以反映边缘已被删除。

例如：呼叫del g [＆＃39; a＆＃39;，＆＃39; e＆＃39;]将不会做任何事情，但是呼叫del g [＆＃39; a＆＃39;＆＃39; c＆＃39;]将将图表更改为：

 {'a': [{'d'},      {'d'}    ],
  'b': [{'c','d'},  set()    ],
  'c': [set(),      {'b','d'}],
  'd': [{'a','c'},  {'a','b'}],
  'e': [set(),      set()    ]}

如果item参数是Graph中的关键节点首先从作为原始节点或目标节点的每个集合中删除该节点。第二，将该节点从边缘删除为密钥。

调用del g [＆＃39; x＆＃39;]将不执行任何操作（没有节点x），但调用del g [＆＃39; a＆＃39;]会将图形更改为：

{'b': [{'c','d'},  set()    ],
'c': [set(),      {'b','d'}],
'd': [{'c'},      {'b'}    ],
'e': [set(),      set()    ]}

但是当我运行delitem函数时，会产生以下错误：

119 # Test __delitem__
122 *Error: del g['a','c'] raised exception TypeError: 'tuple' object is not callable
123 *Error: Failed g.edges == {'a': [{'d'},{'d'}], 'b': [{'c','d'}, set()], 'c': [set(),{'b','d'}], 'd': [{'a','c'},{'a','b'}], 'e': [set(),set()]}
      evaluated: {'b': [{'c', 'd'}, set()], 'e': [set(), set()], 'c': [set(), {'b', 'a', 'd'}], 'a': [{'c', 'd'}, {'d'}], 'd': [{'c', 'a'}, {'b', 'a'}]} == {'b': [{'c', 'd'}, set()], 'e': [set(), set()], 'c': [set(), {'b', 'd'}], 'a': [{'d'}, {'d'}], 'd': [{'c', 'a'}, {'b', 'a'}]}
124 *Error: del g['b','d'] raised exception TypeError: 'tuple' object is not callable
125 *Error: Failed g.edges == {'a': [{'d'},{'d'}], 'b': [{'c'}, set()], 'c': [set(),{'b','d'}], 'd': [{'a','c'},{'a'}], 'e': [set(),set()]}
      evaluated: {'b': [{'c', 'd'}, set()], 'e': [set(), set()], 'c': [set(), {'b', 'a', 'd'}], 'a': [{'c', 'd'}, {'d'}], 'd': [{'c', 'a'}, {'b', 'a'}]} == {'b': [{'c'}, set()], 'e': [set(), set()], 'c': [set(), {'b', 'd'}], 'a': [{'d'}, {'d'}], 'd': [{'c', 'a'}, {'a'}]}
127 *Error: del g['c'] raised exception graph.GraphError: 
128 *Error: Failed g.edges == {'a': [{'d'},{'d'}], 'b': [{'d'}, set()], 'd': [{'a'},{'a','b'}], 'e': [set(),set()]}
      evaluated: {'b': [{'c', 'd'}, set()], 'e': [set(), set()], 'a': [{'c', 'd'}, {'d'}], 'd': [{'c', 'a'}, {'b', 'a'}]} == {'b': [{'d'}, set()], 'e': [set(), set()], 'a': [{'d'}, {'d'}], 'd': [{'a'}, {'b', 'a'}]}
129 *Error: del g['a'] raised exception graph.GraphError: 
130 *Error: Failed g.edges == {'b': [{'d'}, set()], 'd': [set(),{'b'}], 'e': [set(),set()]}
      evaluated: {'b': [{'c', 'd'}, set()], 'e': [set(), set()], 'd': [{'c', 'a'}, {'b', 'a'}]} == {'b': [{'d'}, set()], 'e': [set(), set()], 'd': [set(), {'b'}]}

我不确定有什么问题，有人可以帮我修复我的delitem功能吗？非常感谢。

Answer 1

我写了并测试了这个，它似乎适合你的情况！您遇到了一些问题，例如尝试从集合列表中删除项目而不是集合本身，并且每次调用该方法时都会引发GraphError（因为它不在其他地方）

class Graph(object):
    def __init__(self,*args):
        self.edges = {} 

    def __delitem__(self,item):
        if type(item) == tuple:
            src, dest = item
            if src in self.edges: # This concisely checks if key in dict
                self.edges[src][0].remove(dest) # note 1
                self.edges[dest][1].remove(src) # note 1
        elif item in self.edges:
            del self.edges[item]
            for value in self.edges.values():
               if item in value[0]:
                   value[0].remove(item)
               if item in value[1]:
                   value[1].remove(item)
        else:
            raise GraphError


#################
#### Tests:  ####
#################
g=Graph()
g.edges = \
 {'a': [{'d'},      {'d'}    ],
  'b': [{'c','d'},  set()    ],
  'c': [set(),      {'b','d'}],
  'd': [{'a','c'},  {'a','b'}],
  'e': [set(),      set()    ]}

del g['a']

from pprint import pprint # For pretty printing
pprint(g.edges)

del g[('d','c')]
pprint(g.edges)

如何修复delitem方法

1 个答案:

如何修复__delitem__方法

1 个答案:

如何修复delitem方法