Package dev.frostlake.functions.aggregate

Class RegrR2

java.lang.Object
dev.frostlake.functions.BuiltInFunction
dev.frostlake.functions.AggregateFunction
dev.frostlake.functions.aggregate.RegrR2
public class RegrR2 extends AggregateFunction
REGR_R2(y, x) — coefficient of determination (R squared) over non-null (y, x) pairs (y dependent, x independent). See RegrAccumulator.

  • Constructor Details

    • RegrR2

      public RegrR2()

  • Method Details

    • createAccumulator

      public AggregateFunction.Accumulator createAccumulator()
      Description copied from class: AggregateFunction
      Creates the fresh, empty per-group state for one evaluation of this aggregate; the executor makes one per group (or per window partition) and never shares them.
      Specified by:
      createAccumulator in class AggregateFunction
      Returns:
      a new accumulator starting from this aggregate's empty-group state

    • evaluate

      public Object evaluate(List<Object> args)
      Description copied from class: BuiltInFunction
      Computes the function's result over its already-evaluated argument values. A SQL NULL argument arrives as Java null, and returning null makes the SQL result NULL.
      Specified by:
      evaluate in class BuiltInFunction
      Parameters:
      args - the argument values, in call order
      Returns:
      the function's value for these arguments, or null for SQL NULL

    • getMinArgCount

      public int getMinArgCount()
      Description copied from class: BuiltInFunction
      The fewest arguments a call to this function may pass; fewer is an argument-count error.
      Specified by:
      getMinArgCount in class BuiltInFunction
      Returns:
      the minimum accepted argument count

    • getMaxArgCount

      public int getMaxArgCount()
      Description copied from class: BuiltInFunction
      The most arguments a call to this function may pass; Integer.MAX_VALUE marks a variadic function (see BuiltInFunction.isVariadic()).
      Specified by:
      getMaxArgCount in class BuiltInFunction
      Returns:
      the maximum accepted argument count

    • semiStructuredRejection

      public SemiStructuredRejection semiStructuredRejection(int position)
      REGR_R2 squares both of its inputs, so it reports the same internal multiplication the moment aggregates do and names the OFFENDING type on both sides whichever position it arrived in: live REGR_R2(o, n) and REGR_R2(n, o) are each "Invalid argument types for function '*': (OBJECT, OBJECT)". The rest of the REGR family is deliberately NOT declared — REGR_COUNT, REGR_AVGX and REGR_SXX ACCEPT an OBJECT in the y position live, and REGR_SLOPE / REGR_INTERCEPT / REGR_AVGY / REGR_SYY fail through a desugared TO_DOUBLE plan Frostlake does not have.
      Overrides:
      semiStructuredRejection in class BuiltInFunction
      Parameters:
      position - the zero-based argument position being asked about
      Returns:
      the refusal this position gives a semi-structured value, or NONE when undeclared

    • temporalRejection

      public SemiStructuredRejection temporalRejection(int position)
      A BOOLEAN, a temporal or a BINARY argument is refused at compile time in the multiplication's name with the type twice — "Invalid argument types for function '*': (DATE, DATE)" — exactly as a semi-structured one is: live reaches its internal sum of squares first (live-verified).
      Overrides:
      temporalRejection in class BuiltInFunction
      Parameters:
      position - the zero-based argument position being asked about
      Returns:
      the refusal this position gives a temporal value; by default none

    • booleanRejection

      public SemiStructuredRejection booleanRejection(int position)
      Description copied from class: BuiltInFunction
      The refusal this position gives a declared BOOLEAN argument. Membership is declared per function and never assumed for a family: the whole NUMERIC family (NumericArgumentFunction) refuses a SQL BOOLEAN at compile time in every position — "Invalid argument types for function 'ABS': (BOOLEAN)", MOD(1, TRUE) listing "(NUMBER(1,0), BOOLEAN)" — while the SAME value inside a VARIANT converts to 1.0, and the conditionals (NULLIF(b, 0), NULLIFZERO(b)) take it. The rule reads the DECLARED type, like every channel here.
      Overrides:
      booleanRejection in class BuiltInFunction
      Parameters:
      position - the zero-based argument position being asked about
      Returns:
      the refusal this position gives a BOOLEAN value; by default none

    • binaryRejection

      public SemiStructuredRejection binaryRejection(int position)
      Description copied from class: BuiltInFunction
      The refusal a position gives a statically BINARY-typed value.

      A fifth question rather than a reuse of any of the four above, because BINARY sits on the opposite side of them: it is a scalar a text function is happy to be handed almost everywhere — live answers LENGTH(bn), SUBSTR(bn, 1, 1), CONCAT(bn, bn) — where an OBJECT is refused. Only the functions that read their argument AS TEXT and would have to decode it refuse one, and they say so themselves: VALIDATE_UTF8(bn) and TRY_VALIDATE_UTF8(bn) are "Invalid argument types for function 'TRY_VALIDATE_UTF8': (BINARY(5))" while the same call over a VARCHAR, and even over a NUMBER, returns a value.

      The default is NONE: undeclared means unconstrained, as for the other four.

      Overrides:
      binaryRejection in class BuiltInFunction
      Parameters:
      position - the zero-based argument position being asked about
      Returns:
      the refusal this position gives a BINARY value; by default none