[Tutor] how to understand unhashable type: 'list'

[lina]

Thanks for all. Everything new to me is so amazing.

Well, still a remaining question, how to sort based on the value of the key.

Actually I googled hours ago, wanna see more ways of doing it.

Best regards,

>
> On 17 November 2011 14:04, lina <lina.lastname at gmail.com> wrote:
>>
>> >> Traceback (most recent call last):
>> >>  File "<pyshell#292>", line 1, in <module>
>> >>    weight[list1[0]]=1
>> >> TypeError: unhashable type: 'list'
>> >
>> > You are trying to store a list as a key inside a dict. This cannot be
>> > done
>> > because lists (like all mutable types) can't be hashed.
>>
>> I checked online dictionary, still confused about hashed. is it equal
>> to mix together or mess together?
>
> No.... you need to think programming/computer science where hash/hashing has
> a different meaning.  See wikipedia:
> http://en.wikipedia.org/wiki/Hash_function
> http://en.wikipedia.org/wiki/Hash_table
>
> Also see the description for "hashable" in the Python glossary:
> http://docs.python.org/glossary.html#hashable
>
> Basically hashing is a way to convert something (often a string) into an
> identifying number (not neccesarily but usually unique) in order to use this
> number as a token for the original thing.  Aside, you can infer that that
> because the "dict" code complains about hashing implies that dicts
> themselves are essentially implemented as hash tables... ;)
>
> HTH,
>
> Walter
>
>
>
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