Johannes Bauer wrote:
Hi group,
I have a very simple about sets. This is a minimal example:
#!/usr/bin/python
class x():
def __init__(self, y):
self.__y = y
def __eq__(self, other):
return self.__y == other.__y
def __hash__(self):
return hash(self.__y)
a = x("foo")
s = set([x("bar"), x("moo"), a])
z = x("foo")
print("z = ", z)
print(s)
for i in s:
print(i, i == a, i is a, i == z, i is z)
The problem is: two instances of x() are equal (__eq__ returns true),
but they are not identical. I have an equal element ("z"), but want to
get the *actual* element ("a") in the set. I.d. in the above example,
i'd like something like:
print(s.getelement(z) is a)
True
Is there something like the "getelement" function? How can I do what I want?
No. but you pratically wrote it: in your code, when i == z, then i is
the element you want.
def getelement(sset, item):
for i in sset:
if i == item: return i
The only use for this is see, though, is getting the representative of
an equivalence class from any member thereof.
tjr
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