Re: [Databionic-ESOM-User] features

[<fa...@in...>]

you have to encode them by numbers because labels like "green" or "hot"
will not be read by the program.

i think encoding something like
  age: "1-10","11-20","20-45","45-60" as 1,2,3,4
or
  gender: "male", "female" as 0,1
will give intuitive results using the Euclidean distance.
if you have something like
  color: "green","red","blue","yellow","black"
however, it is unclear what is the best encoding. if you use 1..5, then
you get
  (green-black)^2 = 16
and
  (blue-yellow)^2 = 2
as component in the sum of an Euclidean distance. Is that justified if
all you want to express is "different color"? In this case it might be
better to use 5 binary variables for each color. This is a general
problem in data mining, however, and not ESOM specific.

bye
fabian

p.s. please answer to the list.

mit...@we... wrote:
> I don't want to use special symbolic distance functions. I use the
> euclidean distance. Do you think that by using some symbolic features
> after encoding them to numbers (e.g. 0,1) will contribute positively to
> the classification of the datasets?
> 
> 
>>You can certainly feed ordinal or nominal attributes to the tools if you
>>encode them e.g. as natural numbers. Letters or strings are not allowed
>>as data entries in *.lrn files.
>>
>>The question is, whether Euclidean (or any other implemented distance
>>function) is meaningful on this encoding for your data. Further, the
>>final prototypes that are assigned to each neuron, will almost surely
>>not consist of natural numbers, since the udating of the map uses small
>>vector differences as learning steps. But they could be seen as
>>approximations to symbolic prototypes.
>>
>>If you want to use special symbolic distance functions (e.g. Hamming)
>>you would have to implement them first and I can give you hints on how
>>to do it. In addition, the update step should be modified accordingly.
>>Both should be comparatively easy to do.
>>
>>bye
>>fabian
>>
>>mit...@we... wrote:
>>
>>>May we use not only continuous but also symbolic features with ESOM?
>>>thank you in advance,
>>>Katerina
>>>
>>>
>>>
>>>
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