我是Scala的新手。我想要做的是创建一个名为EnhancedFirstOrderMinimizer
的抽象类,它扩展另一个名为FirstOrderMinimizer
的抽象类。但是,IDE告诉我" Type mismatch, expected: nothing, actual: DF
"。
这是FirstOrderMinimizer:
abstract class FirstOrderMinimizer[T, DF <: StochasticDiffFunction[T]]
(maxIter: Int = -1, tolerance: Double = 1E-6, improvementTol: Double = 1E-3,
val minImprovementWindow: Int = 10,
val numberOfImprovementFailures: Int = 1)
(implicit space: NormedModule[T, Double])
extends Minimizer[T, DF] with SerializableLogging {
protected def initialHistory(f: DF, init: T): History
...
type History
protected def initialHistory(f: DF, init: T): History
protected def adjustFunction(f: DF): DF = f
protected def adjust(newX: T, newGrad: T, newVal: Double): (Double, T) =
(newVal, newGrad)
protected def chooseDescentDirection(state: State, f: DF): T
protected def determineStepSize(state: State, f: DF, direction: T): Double
protected def takeStep(state: State, dir: T, stepSize:Double): T
protected def updateHistory(newX: T, newGrad: T, newVal: Double,
f: DF, oldState: State): History
def iterations(f: DF, init: T): Iterator[State] = {
val adjustedFun = adjustFunction(f)
infiniteIterations(f, initialState(adjustedFun, init))
.takeUpToWhere(_.converged)
}
...
}
以下是EnhancedFirstOrderMinimizer
:
EnhancedFirstOrderMinimizer[T, DF<:StochasticDiffFunction[T]]
(maxIter: Int = -1, tolerance: Double=1E-6, improvementTol: Double=1E-3)
extends FirstOrderMinimizer {
override def iterations(f: DF, init: T): Iterator[State] = {
val adjustedFun = adjustFunction(f)
// f: Type mismatch, expected: nothing, actual: DF
infiniteIterations(f, initialState(adjustedFun, init))
.takeUpToWhere(_.converged)
}
}
你能帮我看一下吗?
答案 0 :(得分:3)
编译器告诉您f
的第一个参数infiniteIterations
是错误的类型。我们可能需要查看声明infiniteIterations
的位置,以确切知道发生了什么。
但我认为对您的扩展程序问题的快速回答是extends FirstOrderMinimizer
应更改为extends FirstOrderMinimizer[T, DF]
。