Hi Lina On 17 November 2011 14:04, lina <lina.lastn...@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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