Attribute test Each recursive step of the tree-growing process must select an attribute test condition to divide the records into smaller subsets To implement this step, the algorithm must provide A method for specifying the test condition for different attribute types and An objective measure for evaluating the goodness of each test condition 1/30/2021 PATTERN RECOGNITION
Attribute test Each recursive step of the tree-growing process must select an attribute test condition to divide the records into smaller subsets. To implement this step, the algorithm must provide ◦ A method for specifying the test condition for different attribute types and ◦ An objective measure for evaluating the goodness of each test condition. 1/30/2021 PATTERN RECOGNITION 11
Attribute test Binary attributes The test condition for a binary attribute generates two possible outcomes Be Temperature Warm- Cold. blooded blooded 1/30/2021 PATTERN RECOGNITION
Attribute test Binary attributes ◦ The test condition for a binary attribute generates two possible outcomes. 1/30/2021 PATTERN RECOGNITION 12
Attribute test Nominal attributes A nominal attribute can produce binary or multiway splits There are 2-1-1 ways of creating a binary partition of n attribute values For a multiway split the number of outcomes depends on the number of distinct values for the corresponding attribute 1/30/2021 PATTERN RECOGNITION
Attribute test Nominal attributes ◦ A nominal attribute can produce binary or multiway splits. ◦ There are 2 N-1 -1 ways of creating a binary partition of N attribute values. ◦ For a multiway split, the number of outcomes depends on the number of distinct values for the corresponding attribute. 1/30/2021 PATTERN RECOGNITION 13
Attribute test Marital Status Divorced Married (a)Multiway split Marital Marital Marital Status Status Status OR OR Married ( Single Single)(Married Single, Divorced Divorced) Divorced Married (b)Binary split(by grouping attribute values) 1/30/2021 PATTERN RECOGNITION
Attribute test 1/30/2021 PATTERN RECOGNITION 14
Attribute test Ordinal attributes Ordinal attributes can also produce binary or multiway splits Ordinal attributes can be grouped as long as the grouping does not violate the order property of the attribute values Shirt Shirt Size Size ∧A La arge, (Small Medium, Large, Medium Extra Large Extra Large 1/30/2021 PATTERN RECOGNITION
Attribute test Ordinal attributes ◦ Ordinal attributes can also produce binary or multiway splits. ◦ Ordinal attributes can be grouped as long as the grouping does not violate the order property of the attribute values. 1/30/2021 PATTERN RECOGNITION 15