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c4.5

henilei

i have data, 1 field contais numerical values. how rapid miner split the numerical value using c4.5?

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MariusHelf

Hi,

RapidMiner's Decision Tree tries all possible split values of a numeric attribute and selects the value which produces the best split with respect to the selected criterion.

Best,
Marius

wessel

It uses all values that are the data set right?
Probably, an implementation that uses sorting, can be even faster.
Because you know an optimal split point is always halfway between to data points.

For example, assume you have a numerical axis from left to right (attribute x) and labels A en B (class attribute).

AAAAAAAAAAA|BBBBBBBBBBBBBBBBBBB
----------------------|------------------------------->
v x-axis
optimal split point

As far as I'm aware you can not create some picture where the optimal split point is not half way in between.

ABABABABABABABABABAB
------------------------------------>
x-axis
There is no optimal split point here? Splitting on x here provides 0 information gain.

AAABBA
------|----------->
v x-axis
optimal split point

I hope you get the idea.

By the way, you can actually create data sets like this and see where it splits!