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ID3 Decision Tree Algorithm in C#

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3.05 (44 votes)
21 Oct 2003
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

Comments and Discussions

QuestionBUG Pin
Member 1278277018-Jun-17 23:08
memberMember 1278277018-Jun-17 23:08 
BugThere is an error. totalAmount Pin
Member 1045453319-Jan-17 19:17
memberMember 1045453319-Jan-17 19:17 
QuestionId3 decision tree Pin
Member 1285792118-Nov-16 1:38
memberMember 1285792118-Nov-16 1:38 
QuestionUrgent help - null attribute Pin
Member 1232661616-Feb-16 5:04
memberMember 1232661616-Feb-16 5:04 
Generalhelp me on project for internet advertisement prediction Pin
Member 1131005414-Dec-14 7:24
memberMember 1131005414-Dec-14 7:24 
Questiondecision tree algorithm code Pin
Member 109256204-Jul-14 17:57
memberMember 109256204-Jul-14 17:57 
QuestionHi, can anyone help me to fix these errors? Pin
Kaushik Sampath Kumar24-Mar-13 7:54
memberKaushik Sampath Kumar24-Mar-13 7:54 
QuestionUrgent Help Pin
nidhalhameed11-Nov-12 6:55
membernidhalhameed11-Nov-12 6:55 
Questionneed help in ID3 Decision Tree Algorithm in C# Pin
ramireddyrasagna6-Feb-12 17:29
memberramireddyrasagna6-Feb-12 17:29 
Questionhelp in id3 decision tree algorithm in c# Pin
ramireddyrasagna5-Feb-12 11:26
memberramireddyrasagna5-Feb-12 11:26 
GeneralNice code....but this code just for two class decision Pin
Moch Lutfi27-Jul-11 2:24
memberMoch Lutfi27-Jul-11 2:24 
GeneralRe: Nice code....but this code just for two class decision Pin
Muneer Safi15-Oct-12 21:03
memberMuneer Safi15-Oct-12 21:03 
GeneralRe: Nice code....but this code just for two class decision Pin
Member 109256204-Jul-14 17:54
memberMember 109256204-Jul-14 17:54 
Generalhelp,id3 decision tree Pin
dhanyamc7-Jun-11 21:06
memberdhanyamc7-Jun-11 21:06 
Generalhelp id3 decision tree Pin
dhanyamc7-Jun-11 8:22
memberdhanyamc7-Jun-11 8:22 
GeneralRebuilt based on this code Pin
Tim Claason1-Feb-11 7:28
memberTim Claason1-Feb-11 7:28 
Generalspliting criterion Pin
jamilehy2-Oct-10 12:04
memberjamilehy2-Oct-10 12:04 
QuestionHow you defined new attributes in main? Pin
jamilehy30-Sep-10 17:28
memberjamilehy30-Sep-10 17:28 
AnswerRe: How you defined new attributes in main? Pin
pol_chu2-Oct-10 9:31
memberpol_chu2-Oct-10 9:31 
GeneralRe: How you defined new attributes in main? Pin
jamilehy2-Oct-10 11:40
memberjamilehy2-Oct-10 11:40 
GeneralRe: How you defined new attributes in main? Pin
pol_chu2-Oct-10 19:16
memberpol_chu2-Oct-10 19:16 
GeneralAn error report [modified] Pin
pol_chu9-Sep-10 22:44
memberpol_chu9-Sep-10 22:44 
Generalerror Pin
lqht25-Apr-10 8:05
memberlqht25-Apr-10 8:05 
GeneralError Pin
strepto125-Apr-10 6:21
memberstrepto125-Apr-10 6:21 
Generalhi Pin
rodalyn15-Mar-10 18:15
memberrodalyn15-Mar-10 18:15 

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Posted 21 Oct 2003


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