19.2 Module Array: array operations


val length : 'a array -> int
Return the length (number of elements) of the given array.
val get: 'a array -> int -> 'a
Array.get a n returns the element number n of array a. The first element has number 0. The last element has number Array.length a - 1. Raise Invalid_argument "Array.get" if n is outside the range 0 to (Array.length a - 1). You can also write a.(n) instead of Array.get a n.
val set: 'a array -> int -> 'a -> unit
Array.set a n x modifies array a in place, replacing element number n with x. Raise Invalid_argument "Array.set" if n is outside the range 0 to Array.length a - 1. You can also write a.(n) <- x instead of Array.set a n x.
val make: int -> 'a -> 'a array
val create: int -> 'a -> 'a array
Array.make n x returns a fresh array of length n, initialized with x. All the elements of this new array are initially physically equal to x (in the sense of the == predicate). Consequently, if x is mutable, it is shared among all elements of the array, and modifying x through one of the array entries will modify all other entries at the same time. Raise Invalid_argument if n <= 0 or n > Sys.max_array_length. If the value of x is a floating-point number, then the maximum size is only Sys.max_array_length / 2. Array.create is a deprecated alias for Array.make.
val init: int -> f:(int -> 'a) -> 'a array
Array.init n f returns a fresh array of length n, with element number i initialized to the result of f i. In other terms, Array.init n f tabulates the results of f applied to the integers 0 to n-1.
val make_matrix: dimx:int -> dimy:int -> 'a -> 'a array array
val create_matrix: dimx:int -> dimy:int -> 'a -> 'a array array
Array.make_matrix dimx dimy e returns a two-dimensional array (an array of arrays) with first dimension dimx and second dimension dimy. All the elements of this new matrix are initially physically equal to e. The element (x,y) of a matrix m is accessed with the notation m.(x).(y). Raise Invalid_argument if dimx or dimy is less than 1 or greater than Sys.max_array_length. If the value of e is a floating-point number, then the maximum size is only Sys.max_array_length / 2. Array.create_matrix is a deprecated alias for Array.make_matrix.
val append: 'a array -> 'a array -> 'a array
Array.append v1 v2 returns a fresh array containing the concatenation of the arrays v1 and v2.
val concat: 'a array list -> 'a array
Same as Array.append, but catenates a list of arrays.
val sub: 'a array -> pos:int -> len:int -> 'a array
Array.sub a start len returns a fresh array of length len, containing the elements number start to start + len - 1 of array a. Raise Invalid_argument "Array.sub" if start and len do not designate a valid subarray of a; that is, if start < 0, or len < 0, or start + len > Array.length a.
val copy: 'a array -> 'a array
Array.copy a returns a copy of a, that is, a fresh array containing the same elements as a.
val fill: 'a array -> pos:int -> len:int -> 'a -> unit
Array.fill a ofs len x modifies the array a in place, storing x in elements number ofs to ofs + len - 1. Raise Invalid_argument "Array.fill" if ofs and len do not designate a valid subarray of a.
val blit: src:'a array -> src_pos:int ->
          dst:'a array -> dst_pos:int -> len:int -> unit
Array.blit v1 o1 v2 o2 len copies len elements from array v1, starting at element number o1, to array v2, starting at element number o2. It works correctly even if v1 and v2 are the same array, and the source and destination chunks overlap. Raise Invalid_argument "Array.blit" if o1 and len do not designate a valid subarray of v1, or if o2 and len do not designate a valid subarray of v2.
val to_list: 'a array -> 'a list
Array.to_list a returns the list of all the elements of a.
val of_list: 'a list -> 'a array
Array.of_list l returns a fresh array containing the elements of l.
val iter: f:('a -> unit) -> 'a array -> unit
Array.iter f a applies function f in turn to all the elements of a. It is equivalent to f a.(0); f a.(1); ...; f a.(Array.length a - 1); ().
val map: f:('a -> 'b) -> 'a array -> 'b array
Array.map f a applies function f to all the elements of a, and builds an array with the results returned by f: [| f a.(0); f a.(1); ...; f a.(Array.length a - 1) |].
val iteri: f:(int -> 'a -> unit) -> 'a array -> unit
val mapi: f:(int -> 'a -> 'b) -> 'a array -> 'b array
Same as Array.iter and Array.map respectively, but the function is applied to the index of the element as first argument, and the element itself as second argument.
val fold_left: f:('a -> 'b -> 'a) -> init:'a -> 'b array -> 'a
Array.fold_left f x a computes f (... (f (f x a.(0)) a.(1)) ...) a.(n-1), where n is the length of the array a.
val fold_right: f:('b -> 'a -> 'a) -> 'b array -> init:'a -> 'a
Array.fold_right f a x computes f a.(0) (f a.(1) ( ... (f a.(n-1) x) ...)), where n is the length of the array a.
Sorting
val sort : cmp:('a -> 'a -> int) -> 'a array -> unit;;
Sort an array in increasing order according to a comparison function. The comparison function must return 0 if its arguments compare as equal, a positive integer if the first is greater, and a negative integer if the first is smaller. For example, the compare function is a suitable comparison function. After calling Array.sort, the array is sorted in place in increasing order. Array.sort is guaranteed to run in constant heap space and logarithmic stack space.

The current implementation uses Heap Sort. It runs in constant stack space.
val stable_sort : cmp:('a -> 'a -> int) -> 'a array -> unit;;
Same as Array.sort, but the sorting algorithm is stable and not guaranteed to use a fixed amount of heap memory. The current implementation is Merge Sort. It uses n/2 words of heap space, where n is the length of the array. It is faster than the current implementation of Array.sort.