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BIDENTIFY directive

Identifies specimens using a tree.


TREE = tree Specifies the tree
TESTELEMENT = scalar Specifies which element of the pointer of information stored at each node of the tree contains the test to be done there to determine which subsequent branch to take
TERMINALNODES = scalar, variate or pointer Scalar or variate saving the number or numbers of the terminal nodes reached by a single specimen, or pointer of scalars or variates saving the numbers of the terminal nodes reached by several specimens


X = factors or variates Variables involved in the tests performed in the tree
VALUES = scalars, variates or texts Values of the variables for the specimens to be identified


BIDENTIFY identifies specimens using a classification tree, or a regression tree, or an identification key (as constructed by procedures BCLASSIFICATION, BREGRESSION or BKEY, respectively).

The characteristics of the specimens are specified using the X and VALUES parameters. Each X setting should be one of the factors or variates in the tree, and the corresponding VALUES setting should be a scalar, variate or text defining its values for the specimens. If X is a variate, VALUES may be a scalar if all the specimens have the same x-value (or if there is only one specimen); it will be a variate if there are several specimens with different x-values. VALUES can be also be a scalar or variate if X is a factor. Alternatively, VALUES may be a text (with one or several values) if the factor X has labels.

The tree is supplied by the TREE option. The TESTELEMENT option indicates which element of the pointer of information, stored at each node of the tree, contains the test to be done there. For trees constructed by procedures BCLASSIFICATION, BREGRESSION or BKEY the test element is the second element of the pointers. In trees constructed by BKEY the test is a factor whose (ordinal) level number defines the branch to take from the node. Alternatively, the tests in trees constructed by BCLASSIFICATION and BREGRESSION are simple logical expressions like

X < 1


X .IN. !t(red,blue)

where a “true” result selects the first branch, and a “false” result selects the second. BIDENTIFY allows for expressions containing a single relational operator from the following list:

equality                                    .EQ. or ==

string equality                          .EQS.

non-equality                            .NE. or /= or

string non-equality                   .NES.

less than                                  .LT. or <

less than or equals                  .LE. or <=

greater than                             .GT. or >

greater than or equals             .GE. or >=

inclusion                                  .IN.

non-inclusion                           .NI.

If the factor or variate in the test is not in the list supplied by the X parameter, all the branches from the node must be followed, and the specimen will reach several terminal nodes. All the branches must also be taken if the specimen has a missing value for the X variable in the test.

The TERMINALNODES option saves the numbers of the terminal nodes that the specimens reach in the tree. If there is a single specimen, TERMINALNODES will be a scalar or a variate. If there are several specimens, it will be a pointer of scalars or variates.


Parameters: X, VALUES.

Action with RESTRICT

Any restrictions are ignored.

See also



Commands for: Calculations and manipulation.

Updated on March 8, 2019

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