F#(数组)

数组的定义：

[<EntryPoint>]
let main argv = 
    let iArr1 = [|1; 3; 5; 7; 9|]
    iArr1 |>  printfn "%A" 
    let eArr = [| |]
    eArr |>  printfn "%A" 
    let iArr2 = [|1..5|]
    iArr2 |>  printfn "%A" 
    let iArr3 = [|1..2..10|]
    iArr3 |>  printfn "%A" 
    let iArr4 = [|for i in 0..4 -> 2*i+1 |]
    iArr4 |>  printfn "%A" 
    let fArr1 = [|for i in 10..-2..0 -> 2.0 * (float i) - 0.5|]
    fArr1 |>  printfn "%A" 
    let fArr2 = [|for i in iArr4 -> (float i) / 2.0 |]
    fArr2 |>  printfn "%A" 
    let x = fArr1.[1]
    fArr1.[1] <- 7.2
    fArr1.[2] <- fArr1.[2] * 2.0
    let tpArr1 = [| for x in 3..9 -> (x,x*x) |]
    tpArr1 |>  printfn "%A" 
    (iArr1 = iArr2) |>  printfn "%b"
    (iArr1 = iArr3) |>  printfn "%b"  
    0 // 返回整数退出代码

F#数组定义支持函数式定义，如for表达式等，支持直接比较。当元素的长度与值都相等时则相等，不同数组类型之间是不能比较的。

数组常用函数：

[<EntryPoint>]
let main argv = 
    let arr1 = [|2;4;8|]
    let l1 = arr1.Length
    let arr2 = [|1;3;5;7;9|]
    arr1.CopyTo(arr2,2)
    arr2 |> printfn "%A"
    let arr4 = [|0.5..7.5|]
    arr1.CopyTo(arr4,0)
    let arr5 = Array.create 6 2
    let arr6 = [|1..10|]
    let arr7 = Array.sub arr6 0 4
    arr7 |> printfn "%A"
    arr6 |> printfn "%A"
    let arr8 = Array.append arr5 arr7
    arr8 |> printfn "%A"
    let arr9 = [|"北京";"上海";"天津";"重庆"|]
    let arr10 = Array.zip arr7 arr9
    arr10 |> printfn "%A"
    let arr11,arr12 = Array.unzip arr10
    arr11 |> printfn "%A"
    arr12 |> printfn "%A"
    let arr13 = [|1.6;1.9;1.0;0.7|]
    let arr14 = Array.zip3 arr7 arr9 arr13
    arr14 |> printfn "%A"
    let _,arr15,_ = Array.unzip3 arr14
    arr15 |> printfn "%A"
    let fArr3 = [|6.5;1.2;9.8;4.0;7.35;2.4;7.3;9.5|]
    let x1 = Array.average fArr3
    fArr3 |> printfn "%A"
    let x2 = Array.sum fArr3
    x2 |> printfn "%f"
    let fArr4 = Array.sort fArr3
    fArr4 |> printfn "%A"
    fArr3 |> printfn "%A" // sort 函数不改变数组本身
    Array.sortInPlace fArr3 // sortInPlace 函数对数组本身进行排序处理
    0 // 返回整数退出代码

其实和scala没什么太大的区别，标准函数都支持。

二维数组：

[<EntryPoint>]
let main argv = 
    let mArr1 = Array2D.create 3 4 1
    mArr1 |> printfn "%A"
    mArr1.[2,1] <- 5
    mArr1.[2,2] <- mArr1.[1,1] + mArr1.[2,1]
    mArr1.[2,3] <- 7
    printfn " Length1=%i, length2=%i" (mArr1.GetLength 0) (mArr1.GetLength 1)
    mArr1 |> printfn "%A"
    let msum (arr : int[,]) =
        let sums = Array.create (arr.GetLength 0) 0
        for i = 0 to (arr.GetLength 0) - 1 do
            for j = 0 to (arr.GetLength 1) - 1 do
                sums.[i] <- sums.[i] + arr.[i,j]
        sums
    (msum mArr1) |> printfn "%A" 
    0 // 返回整数退出代码

使用Array2D库创建2维数组msum将每个维度的值求和，最后输出

三维，四维数组：

 let mArr2 = Array3D.create 3 2 3 0.0
    let mArr3 = Array4D.create 2 2 2 3 true
    mArr2.[0,0,0] <- 0.27
    mArr3.[1,1,1,1] <- false

不规则多维数组：

[<EntryPoint>]
let main argv = 
    let mArr4 = [|[|1;1|]; [|1;2;1|]; [|1;3;3;1|]|]
    mArr4 |> printfn "%A"
    mArr4.[0] |> printfn "%A"
    let a = mArr4.[1]
    let b,c = a.[0],mArr4.[2].[2]
    printfn "Length=%i GetLength=%i" mArr4.Length (mArr4.GetLength 0)
    for i=0 to mArr4.Length-1 do 
        printf "[%i].Length=%i " i mArr4.[i].Length
    let arr1 = [|1..4|]
    let arr2 = [|1..2..10|]
    let mArr5 = [|arr1;arr2;[|for i in arr1 -> 1+i|];[|for i in arr2 -> 2*i|]|]
    mArr5 |> printfn "%A"
    0 // 返回整数退出代码

杨辉三角形：

[<EntryPoint>]
let main argv = 
    let yanghui n =
        let arr = Array.create n [|1|]
        printfn "%A" arr
        for i = 1 to n-1 do
            arr.[i] <- (Array.create (i+1) 0)
            arr.[i].[0] <- arr.[i-1].[0]
            for j = 1 to i-1 do
                arr.[i].[j] <- arr.[i-1].[j-1] + arr.[i-1].[j]
            arr.[i].[i] <- arr.[i-1].[i-1]
        arr
    let arr = 10 |> yanghui
    for i in 0..arr.Length-1 do
        printfn "%A" arr.[i]
    0 // 返回整数退出代码