如何替换Scala中的多个存在项?
我有一段代码,它根据所选类别中某个项目的存在来确定服务费用:如何替换Scala中的多个存在项?,scala,Scala,我有一段代码,它根据所选类别中某个项目的存在来确定服务费用: def bill(purchasedItems: List[String]): BigDecimal = { def totalCost: BigDecimal = purchasedItems.foldLeft(BigDecimal(0))((tot, p) => tot + menu(p).price) def serviceChargeRate: BigDecimal = if (purchasedIte
def bill(purchasedItems: List[String]): BigDecimal = {
def totalCost: BigDecimal = purchasedItems.foldLeft(BigDecimal(0))((tot, p) => tot + menu(p).price)
def serviceChargeRate: BigDecimal = if (purchasedItems.exists(name => menu(name).serviceChargeCategory == PremiumItem)) 1.2
else if (purchasedItems.exists(name => menu(name).serviceChargeCategory == Food)) 1.1
else 1.0
totalCost * serviceChargeRate
}
我尝试用collectFirst替换此项,但它将匹配第一项,而不是使用优先级顺序,以确保使用最高的服务费
def bill(purchasedItems: List[String]): BigDecimal = {
def totalCost: BigDecimal = purchasedItems.foldLeft(BigDecimal(0))((tot, p) => tot + menu(p).price)
def serviceChargeRate: Option[BigDecimal] = purchasedItems.map(menu(_).serviceChargeCategory) collectFirst {
case PremiumItem => BigDecimal("1.2")
case Food => BigDecimal("1.1")
}
totalCost * serviceChargeRate.getOrElse(BigDecimal("1.0"))
}
在Scala中是否有更好、更实用的方法来实现这一点,或者我是否必须接受if/else块
谢谢
本我的建议大致如下:
def bill(purchasedItems: List[String]): BigDecimal = {
val totalCost: BigDecimal = purchasedItems.foldLeft(BigDecimal(0))((tot, p) => tot + menu(p).price)
val serviceRate: BigDecimal = purchasedItems.map { item ⇒ menu(item).serviceChargeCategory match {
case "PremiumItem" ⇒ 1.2
case "Food" ⇒ 1.1
case _ ⇒ 1.0
}}.max
totalCost * serviceChargeRate
}
我的建议大致如下:
def bill(purchasedItems: List[String]): BigDecimal = {
val totalCost: BigDecimal = purchasedItems.foldLeft(BigDecimal(0))((tot, p) => tot + menu(p).price)
val serviceRate: BigDecimal = purchasedItems.map { item ⇒ menu(item).serviceChargeCategory match {
case "PremiumItem" ⇒ 1.2
case "Food" ⇒ 1.1
case _ ⇒ 1.0
}}.max
totalCost * serviceChargeRate
}
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