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ID3 Decision Tree Algorithm in C#

, 21 Oct 2003
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Sample of ID3 Decision Tree Algorithm in C#


The algorithm ID3 (Quinlan) uses the method top-down induction of decision trees. Given a set of classified examples a decision tree is induced, biased by the information gain measure, which heuristically leads to small trees. The examples are given in attribute-value representation. The set of possible classes is finite. Only tests, that split the set of instances of the underlying example languages depending on the value of a single attribute are supported.


Depending on whether the attributes are nominal or numerical, the tests either

  • have a successor for each possible attribute value, or
  • split according to a comparison of an attribute value to a constant, or depending on if an attribute value belongs to a certain interval or not.

The algorithm starts with the complete set of examples, a set of possible tests and the root node as the actual node. As long as the examples propagated to a node do not all belong to the same class and there are tests left,

  • a test with highest information gain is chosen,
  • the corresponding set of successors is created for the actual node,
  • each example is propagated to the successor given by the chosen test,
  • ID3 is called recursively for all successors.

How it works

The core of sample is builded with 3 classes (Attribute, TreeNode and DecisionTreeID3).

  • TreeNode - are the nodes of the decision tree;
  • Attribute - is the class with have a name e any possible values;
  • DecisionTreeID3 - is the class what get a data samples and generate a decision tree.


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About the Author

Web Developer iddi
Brazil Brazil
No Biography provided

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Comments and Discussions

Generalhelp me on project for internet advertisement prediction Pin
Member 1131005414-Dec-14 8:24
memberMember 1131005414-Dec-14 8:24 
Questiondecision tree algorithm code Pin
Member 109256204-Jul-14 18:57
memberMember 109256204-Jul-14 18:57 
QuestionHi, can anyone help me to fix these errors? Pin
Kaushik Sampath Kumar24-Mar-13 8:54
memberKaushik Sampath Kumar24-Mar-13 8:54 
QuestionUrgent Help Pin
nidhalhameed11-Nov-12 7:55
membernidhalhameed11-Nov-12 7:55 
Questionneed help in ID3 Decision Tree Algorithm in C# Pin
ramireddyrasagna6-Feb-12 18:29
memberramireddyrasagna6-Feb-12 18:29 
Questionhelp in id3 decision tree algorithm in c# Pin
ramireddyrasagna5-Feb-12 12:26
memberramireddyrasagna5-Feb-12 12:26 
GeneralNice code....but this code just for two class decision Pin
h4ckm03d27-Jul-11 3:24
memberh4ckm03d27-Jul-11 3:24 
GeneralRe: Nice code....but this code just for two class decision Pin
Muneer Safi15-Oct-12 22:03
memberMuneer Safi15-Oct-12 22:03 
GeneralRe: Nice code....but this code just for two class decision Pin
Member 109256204-Jul-14 18:54
memberMember 109256204-Jul-14 18:54 
Generalhelp,id3 decision tree Pin
dhanyamc7-Jun-11 22:06
memberdhanyamc7-Jun-11 22:06 
Generalhelp id3 decision tree Pin
dhanyamc7-Jun-11 9:22
memberdhanyamc7-Jun-11 9:22 
GeneralRebuilt based on this code Pin
Tim Claason1-Feb-11 8:28
memberTim Claason1-Feb-11 8:28 
Generalspliting criterion Pin
jamilehy2-Oct-10 13:04
memberjamilehy2-Oct-10 13:04 
QuestionHow you defined new attributes in main? Pin
jamilehy30-Sep-10 18:28
memberjamilehy30-Sep-10 18:28 
AnswerRe: How you defined new attributes in main? Pin
pol_chu2-Oct-10 10:31
memberpol_chu2-Oct-10 10:31 
GeneralRe: How you defined new attributes in main? Pin
jamilehy2-Oct-10 12:40
memberjamilehy2-Oct-10 12:40 
GeneralRe: How you defined new attributes in main? Pin
pol_chu2-Oct-10 20:16
memberpol_chu2-Oct-10 20:16 
GeneralAn error report [modified] Pin
pol_chu9-Sep-10 23:44
memberpol_chu9-Sep-10 23:44 
Generalerror Pin
lqht25-Apr-10 9:05
memberlqht25-Apr-10 9:05 
GeneralError Pin
strepto125-Apr-10 7:21
memberstrepto125-Apr-10 7:21 
Generalhi Pin
rodalyn15-Mar-10 19:15
memberrodalyn15-Mar-10 19:15 
Generalhelp:id3 decision tree Pin
std_112-Mar-10 2:34
memberstd_112-Mar-10 2:34 
GeneralRe: help:id3 decision tree Pin
SamBarakaba15-Oct-10 23:36
memberSamBarakaba15-Oct-10 23:36 
GeneralRe: help:id3 decision tree Pin
leavetrace25-Oct-10 0:08
memberleavetrace25-Oct-10 0:08 
GeneralRe: help:id3 decision tree Pin
leavetrace25-Oct-10 0:13
memberleavetrace25-Oct-10 0:13 

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