# Package weka.filters.unsupervised.instance

- Class Summary
  Class | Description
  --- | ---
  NonSparseToSparse | An instance filter that converts all incoming instances into sparse format.
  Randomize | Randomly shuffles the order of instances passed through it.
  RemoveDuplicates | Removes all duplicate instances from the first batch of data it receives.
  RemoveFolds | This filter takes a dataset and outputs a specified fold for cross validation.
  RemoveFrequentValues | Determines which values (frequent or infrequent ones) of an (nominal) attribute are retained and filters the instances accordingly.
  RemoveMisclassified | A filter that removes instances which are incorrectly classified.
  RemovePercentage | A filter that removes a given percentage of a dataset.
  RemoveRange | A filter that removes a given range of instances of a dataset.
  RemoveWithValues | Filters instances according to the value of an attribute.
  Resample | Produces a random subsample of a dataset using either sampling with replacement or without replacement.
  ReservoirSample | Produces a random subsample of a dataset using the reservoir sampling Algorithm "R" by Vitter.
  SparseToNonSparse | An instance filter that converts all incoming sparse instances into non-sparse format.
  SubsetByExpression | * Filters instances according to a user-specified expression. * * 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 * | ATTRIBUTE regexp 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. * - regexp * A regular expression for pattern matching, e.g., '^id.*$' * * 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) * * Valid options are: * *