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Comment: Migrated to Confluence 4.0

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Grammar:

boolexpr_list ::= boolexpr_list boolexpr_part | boolexpr_part;

boolexpr_part ::= boolexpr:e {: parser.setResult(e); :} ;

boolexpr ::=    BOOLEAN 
              | true
              | false
              | expr < expr
              | expr <= expr
              | expr > expr
              | expr >= expr
              | expr = expr
              | ( boolexpr )
              | not boolexpr
              | boolexpr and boolexpr
              | boolexpr or boolexpr
              | ATTRIBUTE is STRING
              ;

expr      ::=   NUMBER
              | ATTRIBUTE
              | ( expr )
              | opexpr
              | funcexpr
              ;

opexpr    ::=   expr + expr
              | expr - expr
              | expr * expr
              | expr / expr
              ;

funcexpr ::=    abs ( expr )
              | sqrt ( expr )
              | log ( expr )
              | exp ( expr )
              | sin ( expr )
              | cos ( expr )
              | tan ( expr )
              | rint ( expr )
              | floor ( expr )
              | pow ( expr for base , expr for exponent )
              | ceil ( expr )
              ;

Notes:

  • NUMBER
    any integer or floating point number
    (but not in scientific notation!)
  • STRING
    any string surrounded by single quotes;
    the string may not contain a single quote though.
  • ATTRIBUTE
    the following placeholders are recognized for
    attribute values:
  • CLASS for the class value in case a class attribute is set.
  • ATTxyz with xyz a number from 1 to # of attributes in the
    dataset, representing the value of indexed attribute.

Examples:

  • extracting only mammals and birds from the 'zoo' UCI dataset:
    (CLASS is 'mammal') or (CLASS is 'bird')
  • extracting only animals with at least 2 legs from the 'zoo' UCI dataset:
    (ATT14 >= 2)
  • extracting only instances with non-missing 'wage-increase-second-year'
    from the 'labor' UCI dataset:
    not ismissing(ATT3)

Options

The table below describes the options available for SubsetByExpression.

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