Python，TypeError: unhash 类型: ‘ list’

我在程序中收到以下错误: 追溯:

Traceback (most recent call last):
File "C:\Python33\Archive\PythonGrafos\Alpha.py", line 126, in <module>
menugrafos()
File "C:\Python33\Archive\PythonGrafos\Alpha.py", line 97, in menugrafos
zetta = Beta.caminhografo(grafo,va,vb)
File "C:\Python33\Archive\PythonGrafos\Beta.py", line 129, in caminhografo
if ([vo, a]) in vat == ([vo,vq]) in vat:
TypeError: unhashable type: 'list'

这个程序的目的是制作一个工作良好的邻接列表，然后继续搜索，如果有一个顶点和 vb 之间的路径。我使用了集合/默认设置中的列表字典来适当地附加相邻的顶点。

问题在于在程序末尾创建列表之后的 if 子句。我不能找到一种方法来正确地使用 if 子句与结果，以查看是否有一个有效的路径之间的顶点。此外，grafo 是一个图类。

密码如下:

class graph:
v = 0
a = 0
node = []


class vertex:
ta = []
adj = {}
    

def caminhografo(grafo, va, vb):
vat = defaultdict(list)
i = 0
a = 0
z = 0
vo = int(va)
vq = int(vb)
vz = int(va)
vw = int(vb)
x = len(grafo.node)
if vz < vw:
for vz in range (vw+1):
a = 0
x = len(grafo.node)
for a in range (x):
if [int(vz),int(a)] in grafo.node:
vat[vz].append(a)
if vz > vw:
while vz > vw:
a = 0
x = len(grafo.node)
for a in range (x):
if[int(va),int(a)] in grafo.node:
vat[vz].append(a)
vz = vz - 1
a = 0
x = len(grafo.node)
print(vat)
for a in range (x):
if ([vo, a]) in vat == ([vo,vq]) in vat:
print("""
==============================================
Existe Caminho
==============================================
""")
break
elif ([vo,a]) in vat:
vo = a
else:
print("""
==============================================
Não Existe Caminho
==============================================
""")
break

谢谢你的帮助。

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最佳答案

The problem is that you can't use a list as the key in a dict, since dict keys need to be immutable. Use a tuple instead.

This is a list:

[x, y]

This is a tuple:

(x, y)

Note that in most cases, the ( and ) are optional, since , is what actually defines a tuple (as long as it's not surrounded by [] or {}, or used as a function argument).

You might find the section on tuples in the Python tutorial useful:

Though tuples may seem similar to lists, they are often used in different situations and for different purposes. Tuples are immutable, and usually contain an heterogeneous sequence of elements that are accessed via unpacking (see later in this section) or indexing (or even by attribute in the case of namedtuples). Lists are mutable, and their elements are usually homogeneous and are accessed by iterating over the list.

And in the section on dictionaries:

Unlike sequences, which are indexed by a range of numbers, dictionaries are indexed by keys, which can be any immutable type; strings and numbers can always be keys. Tuples can be used as keys if they contain only strings, numbers, or tuples; if a tuple contains any mutable object either directly or indirectly, it cannot be used as a key. You can’t use lists as keys, since lists can be modified in place using index assignments, slice assignments, or methods like append() and extend().

In case you're wondering what the error message means, it's complaining because there's no built-in hash function for lists (by design), and dictionaries are implemented as hash tables.


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