给定一个整数列表，我们可以执行以下操作来获取不同值的列表。
let myList = [ 1; 2; 2; 3; 4; 3 ]
let distinctList = myList |> Seq.distinct |> List.ofSeq
但是，在我的例子中，我有一个定义如下的自定义类型列表:
type Listing(fromDate:NSDate, toDate:NSDate, pricePerNight:int, landlordId:String, landlordName:String, listingId:String, pic1url:NSUrl, pic2url:NSUrl, pic3url:NSUrl, pic4url:NSUrl, pic5url:NSUrl, postcode:String, latitude:Double, longitude:Double, location:String, partnername:String,partnerid:String) =
member this.fromDate : NSDate = fromDate
member this.toDate : NSDate = toDate
member this.pricePerNight : int = pricePerNight
member this.landlordId : String = landlordId
member this.landlordName : String = landlordName
member this.listingId : String = listingId
member this.pic1url : NSUrl = pic1url
member this.pic2url : NSUrl = pic2url
member this.pic3url : NSUrl = pic3url
member this.pic4url : NSUrl = pic4url
member this.pic5url : NSUrl = pic5url
member this.postcode : String = postcode
member this.latitude : Double = latitude
member this.longitude : Double = longitude
member this.location : String = location
member this.partnername : String = partnername
member this.partnerid : String = partnerid
接下来我有一个定义如下的列表:
let mutable listings : List<Listing> = List.Empty
现在我想过滤此列表以仅获取唯一值(如果值具有唯一的 listingId，则该值是唯一的)。我可以用天真的方式做到这一点并将所有 listingId 添加到字符串列表中，对字符串列表执行不同的操作，然后提取具有不同列表中的 id 的列表，但我认为必须有更好的方法。
最佳答案
您可以使用 Seq.distinctBy使用 lambda 函数来获取您想要的唯一性值:
listings |> Seq.distinctBy (fun l -> l.listingId)
关于.net - 从自定义类型 F# 的列表中过滤不同的值，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/48975980/