Ah, now I see it is actually mentioned in the documentation, because I was
reading part for SetPartition, not for SetPartitionS...
Dne úterý 15. února 2022 v 10:38:46 UTC+1 uživatel mitchondra napsal:
> To be honest, I really did not find the error message helpfull and I
> identified the problem mostly just by "common programmer sense". But, of
> course, I am not that familiar with Sage.
>
> I basically just used the examples of SetPartitions constructor, since I
> found no general explanation what are possible arguments of this
> constructor and what the arguments are supposed to fullfil.
> I guess it makes sense to allow only sorted list of sizes (as per
> definition of integer partition), but it should be mentioned somewhere in
> documentation then.
>
> Best,
> Ondra
>
> Dne úterý 15. února 2022 v 0:34:35 UTC+1 uživatel Travis Scrimshaw napsal:
>
>> As Martin said, this is not a bug. However, the error message itself is
>> slightly vague because it only states partition. We could simply run
>> sorted(part, reverse=True) before passing it off to create the Partition in
>> the SetPartitions __classcall__. This would make the behavior less
>> surprising, and our output does not match the input sizes (since it is lex
>> based). I think we probably just didn't think about normalizing input here.
>>
>> Also, I found this bug:
>>
>> sage: SP = SetPartitions(10, [4,3,2,1])
>> sage: SP.random_element()
>> {{1, 2, 4, 5, 7, 8}, {3, 6}, {9}, {10}}
>>
>> Best,
>> Travis
>>
>>
>> On Tuesday, February 15, 2022 at 1:51:32 AM UTC+9 axio...@yahoo.de wrote:
>>
>>> The argument providing the block sizes is required to be an integer
>>> partition (or something that sage can make into an integer partition), as
>>> the error message indicates.
>>>
>>> One might argue that Partition (and hence SetPartition) should take
>>> lists in any order, but this would also increase the likelihood of typos
>>> going undetected, I guess.
>>>
>>> Martin
>>>
>>> On Monday, 14 February 2022 at 13:02:39 UTC+1 mitch...@gmail.com wrote:
>>>
>>>> Hello,
>>>>
>>>> I am currently working with set partitions and I encountered possible
>>>> bug when creating SetPartitions instance with specified partition sizes:
>>>>
>>>> ```
>>>> sage: SetPartitions(10, [4,3,2,1])
>>>>
>>>> Set partitions of {1, 2, 3, 4, 5, 6, 7, 8, 9, 10} with sizes in [4, 3,
>>>> 2, 1]
>>>> ```
>>>>
>>>> The above works, but changing the order of sizes gives error:
>>>> ```
>>>> sage: SetPartitions(10, [1,2,3,4])
>>>>
>>>>
>>>>
>>>>
>>>> ---------------------------------------------------------------------------
>>>> ValueError Traceback (most recent call
>>>> last)
>>>> <ipython-input-4-90164a225d10> in <module>
>>>> ----> 1 SetPartitions(Integer(10),
>>>> [Integer(1),Integer(2),Integer(3),Integer(4)])
>>>>
>>>> /usr/lib/python3/dist-packages/sage/misc/classcall_metaclass.pyx in
>>>> sage.misc.classcall_metaclass.ClasscallMetaclass.__call__
>>>> (build/cythonized/sage/misc/classcall_metaclass.c:1714)()
>>>> 332 """
>>>> 333 if cls.classcall is not None:
>>>> --> 334 return cls.classcall(cls, *args, **kwds)
>>>> 335 else:
>>>> 336 # Fast version of type.__call__(cls, *args, **kwds)
>>>>
>>>> /usr/lib/python3/dist-packages/sage/combinat/set_partition.py in
>>>> __classcall_private__(cls, s, part)
>>>> 2025 else:
>>>> 2026 if part not in Partitions(len(s)):
>>>> -> 2027 raise ValueError("part must be a partition
>>>> of %s"%len(s))
>>>> 2028 else:
>>>> 2029 return SetPartitions_setparts(s,
>>>> Partition(part))
>>>>
>>>> ValueError: part must be a partition of 10
>>>> ```
>>>>
>>>> Other orders od partition sizes (other than descending) also gives the
>>>> same error:
>>>> ```
>>>> sage: SetPartitions(10, [4,2,3,1])
>>>> <the same error as above>
>>>> ```
>>>>
>>>> Diferent sets also show this behavior:
>>>> ```
>>>> sage: SetPartitions(8, [4,3,1])
>>>> <OK>
>>>>
>>>>
>>>>
>>>> ```
>>>>
>>>> ```
>>>> sage: SetPartitions(8, [4,3,1])
>>>>
>>>> <Error>
>>>> ```
>>>>
>>>> The same happens when using sage as a module within Python
>>>>
>>>> I am using Sage version 9.0, using Python 3.8.10.
>>>> Operating system is Ubuntu 20.04.3 (64bit)
>>>>
>>>> Best regards,
>>>> Ondra
>>>>
>>>
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