FSharp-07-Collections-Mutable

Array

创建操作

步长为1的数组

let a = [|0..10|]
printfn $"%A{a}"

[|0; 1; 2; 3; 4; 5; 6; 7; 8; 9; 10|]

步长为2的数组

let a = [|1..2..10|]
// [|1; 3; 5; 7; 9|]
printfn $"%A{a}"
a

index	value
0	1
1	3
2	5
3	7
4	9

步长为-2的数组

let a=[|10.. -2 ..0|]
a

index	value
0	10
1	8
2	6
3	4
4	2
5	0

创建数组的其他方式

let arr123 = [|
    1
    2
    3 |]
arr123

index	value
0	1
1	2
2	3

let arrOfSquares = [| for i in 0 .. 10 -> i*i |]
arrOfSquares

index	value
0	0
1	1
2	4
3	9
4	16
5	25
6	36
7	49
8	64
9	81
10	100

切片操作

a[1..5]

let a=[|0..10|]
// [|0; 1; 2; 3; 4; 5; 6; 7; 8; 9; 10|]
printfn $"%A{a}"
a[1..5]

index	value
0	1
1	2
2	3
3	4
4	5

a[..2]

let a=[|0..10|]
// [|0; 1; 2; 3; 4; 5; 6; 7; 8; 9; 10|]
printfn $"%A{a}"

a[..2]

index	value
0	0
1	1
2	2

a[5..]

let a=[|0..1..10|]
a[5..]

index	value
0	5
1	6
2	7
3	8
4	9
5	10

a[5..2]

let a=[|0..1..10|]
a[5..2]

// (empty)

常规操作

Lists use square brackets and ; delimiter

// Lists use square brackets and `;` delimiter
let arr1 = [| "a"; "b" |]
printfn $"%A{arr1}" 

[|”a”; “b”|]

添加元素

// :: is prepending
//let arr2 = "c" :: arr1
let arr2 = Array.append [|"c"|] arr1
printfn $"%A{arr2}"

[|”c”; “a”; “b”|]

连接数组

// @ is concat    
//let arr3 = arr1 @ arr2   
let arr3 = Array.append arr1 arr2
printfn $"%A{arr3}"
Array.append [|"c"|] arr1

[|”a”; “b”; “c”; “a”; “b”|]

index	value
0	c
1	a
2	b

let arr1 = [| 1; 2; 3 |]

> 常见API

printfn $"%A{arr1}"
// functions
printfn "Array.isEmpty is %b" (Array.isEmpty arr1)
printfn "Array.length is %d" (arr1 |>Array.length)
printfn "Array.head is %d" (arr1 |>Array.head)
printfn "Array.tail.head is %d" (arr1 |>Array.tail   |>Array.head)
printfn "Array.tail.tail.head is %d" (arr1 |>Array.tail |>Array.tail |>Array.head)
printfn "Array.item 1  is %d" (arr1 |>Array.item 1)
arr1

[|1; 2; 3|]
Array.isEmpty is false
Array.length is 3
Array.head is 1
Array.tail.head is 2
Array.tail.tail.head is 3
Array.item 1 is 2
| index | value |
| ———- | ——- |
| 0 | 1 |
| 1 | 2 |
| 2 | 3 |

zip与unzip

// in[]

let arr1 = [| 1; 2; 3 |]
let arr2 = [| 4; 5; 6 |]
let arr3 = Array.zip arr1 arr2
printfn $"{arr3}"
// list<'t*'u> -> list<'t> * list<'u>
let arr4,arr5 = Array.unzip arr3
printfn $"{arr4}"
printfn $"{arr5}"

// out[] 

System.Tuple`2[System.Int32,System.Int32][]
System.Int32[]
System.Int32[]

arr3
| index | Item1 | Item2 |
| ———- | ——- | ——- |
| 0 | 1 | 4 |
| 1 | 2 | 5 |
| 2 | 3 | 6 |

arr4
| index | value |
| ———- | ——- |
| 0 | 1 |
| 1 | 2 |
| 2 | 3 |

arr5
| index | value |
| ———- | ——- |
| 0 | 4 |
| 1 | 5 |
| 2 | 6 |

Contains

let arr1 = [| 1; 2; 3 |]
// value:'t -> 't list -> bool
Array.contains 1 arr1
// True

赋值

let arr1 = [| 1; 2; 3 |]
arr1[0] <- 10
arr1

index	value
0	10
1	2
2	3

注意区分

注意区别：逗号：元组，分号：元素

元组

[|"a","b","c"|]

index	Item1	Item2	Item3
0	a	b	c

元素

[|"a";"b";"c"|]

index	value
0	a
1	b
2	c

Dictionary

定义字典

let d=
    [
    (1,"cyan")
    (2,"chau")
    ]
    
    |> dict

d    

key	value
1	cyan
2	chau

遍历操作

d[2]

chau

查找操作

d.ContainsKey(1)

my_dict.ContainsKey(1)

True

注意

// d.Add(1, "X")
//Error: System.NotSupportedException: 无法转变此值

添加操作

open System.Collections.Generic
let my_dict = Dictionary<_,_>(d)
my_dict.Add(3,"X")
my_dict

key	value
1	cyan
2	chau
3	X

// TryAdd 尝试添加，添加失败，返回原先字典
my_dict.TryAdd(3,"Y")
my_dict.TryAdd(1,"Y")
my_dict

key	value
1	cyan
2	chau
3	X

计数操作

my_dict.Count

3

取键操作

my_dict.Keys

index	value
0	1
1	2
2	3

取值操作

my_dict.Values

index	value
0	cyan
1	chau
2	X

HashSet

创建操作

open System.Collections.Generic
let h = HashSet<_>([1;2;3])
h

index	value
0	1
1	2
2	3

添加操作

h.Add(4)
h.Add(5)
h.Add(6)
h

index	value
0	1
1	2
2	3
3	4
4	5
5	6

example

let set_1 = [1;2;3;0;-1;1;1;] |> HashSet
let set_2 = [1;2;3;5;6;7] |> HashSet
printfn $"%A{set_1}"
printfn $"%A{set_2}"

seq [1; 2; 3; 0; …]
seq [1; 2; 3; 5; …]

// 是否为子集
set_1.IsSubsetOf(set_2)

False

// 并集
set_1.UnionWith(set_2)
set_1

index	value
0	1
1	2
2	3
3	0
4	-1
5	5
6	6
7	7

// 交集
set_1.IntersectWith(set_2)
set_1

index	value
0	1
1	2
2	3

System.Collections.Generic

包含用于定义泛型集合的接口和类，可允许用户创建强类型集合，以提供比非泛型强类型集合更好的类型安全性和性能。
官方文档