Module Array


module Array: Extlib.ExtArray.Array
Array operations.

Arrays are mutable data structures with a fixed size, which support fast access and modification, and are used pervasively in imperative computing. While arrays are completely supported in OCaml, it is often a good idea to investigate persistent alternatives, such as lists or hash maps.

A variant of arrays, arrays with capabilities, is provided in module Array.Cap. This notion of capabilities permit the transformation of a mutable array into a read-only or a write-only arrays, without loss of speed and with the possibility of distributing different capabilities to different expressions.
Author(s): Xavier Leroy, Richard W.M. Jones, David Teller


type 'a t = 'a array 
The type of arrays.
include Array.Enumerable
include Array.Mappable

Base 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. You can also write a.(n) instead of Array.get a n.
Raises Invalid_argument "index out of bounds" if n is outside the range 0 to (Array.length a - 1).
val set : 'a array -> int -> 'a -> unit
Array.set a n x modifies array a in place, replacing element number n with x. You can also write a.(n) <- x instead of Array.set a n x.
Raises Invalid_argument "index out of bounds" if n is outside the range 0 to Array.length a - 1.

Constructors

val make : 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.
Raises 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.
val create : int -> 'a -> 'a array
Deprecated.Array.create is an alias for Array.make.
val init : int -> (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.
Raises Invalid_argument if n < 0 or n > Sys.max_array_length. If the return type of f is float, then the maximum size is only Sys.max_array_length / 2.
val make_matrix : int -> 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).
Raises Invalid_argument if dimx or dimy is negative 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.
val create_matrix : int -> int -> 'a -> 'a array array
Deprecated.Array.create_matrix is an alias for Array.make_matrix.

Iterators

val iter : ('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 : ('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 : (int -> 'a -> unit) -> 'a array -> unit
Same as Array.iter, but the function is applied to the index of the element as first argument, and the element itself as second argument.
val mapi : (int -> 'a -> 'b) -> 'a array -> 'b array
Same as Array.map, but the function is applied to the index of the element as first argument, and the element itself as second argument.
val fold_left : ('a -> 'b -> 'a) -> '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 : ('a -> 'b -> 'b) -> 'a array -> 'b -> 'b
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.
val reduce : ('a -> 'a -> 'a) -> 'a array -> 'a
Array.reduce f a is fold_left f a.(0) a.(1 .. n-1).
Raises Invalid_argument on empty arrays.
val max : 'a array -> 'a
max a returns the largest value in a as judged by Pervasives.compare
val min : 'a array -> 'a
min a returns the smallest value in a as judged by Pervasives.compare

Operations on two arrays

val iter2 : ('a -> 'b -> unit) -> 'a array -> 'b array -> unit
Array.iter2 f [|a1; ...; an|] [|b1; ...; bn|] performs calls f a1 b1; ...; f an bn in that order.
Raises Invalid_argument if the length of a1 does not equal the length of a2.
val iter2i : (int -> 'a -> 'b -> unit) -> 'a array -> 'b array -> unit
Array.iter2i f [|a1; ...; an|] [|b1; ...; bn|] performs calls f 0 a1 b1; ...; f (n - 1) an bn in that order.
Raises Invalid_argument if the length of a1 does not equal the length of a2.

Predicates

val for_all : ('a -> bool) -> 'a array -> bool
for_all p [a1; ...; an] checks if all elements of the array satisfy the predicate p. That is, it returns (p a1) && (p a2) && ... && (p an).
val exists : ('a -> bool) -> 'a array -> bool
exists p [a1; ...; an] checks if at least one element of the array satisfies the predicate p. That is, it returns (p a1) || (p a2) || ... || (p an).
val find : ('a -> bool) -> 'a array -> 'a
find p a returns the first element of array a that satisfies the predicate p.
Raises Not_found if there is no value that satisfies p in the array a.
val mem : 'a -> 'a array -> bool
mem m a is true if and only if m is equal to an element of a.
val memq : 'a -> 'a array -> bool
Same as Array.mem but uses physical equality instead of structural equality to compare array elements.
val findi : ('a -> bool) -> 'a array -> int
findi p a returns the index of the first element of array a that satisfies the predicate p.
Raises Not_found if there is no value that satisfies p in the array a.
val filter : ('a -> bool) -> 'a array -> 'a array
filter p a returns all the elements of the array a that satisfy the predicate p. The order of the elements in the input array is preserved.
val filter_map : ('a -> 'b option) -> 'a array -> 'b array
filter_map f e returns an array consisting in all elements x such that f y returns Some x , where y is an element of e.
val find_all : ('a -> bool) -> 'a array -> 'a array
find_all is another name for Array.filter.
val partition : ('a -> bool) -> 'a array -> 'a array * 'a array
partition p a returns a pair of arrays (a1, a2), where a1 is the array of all the elements of a that satisfy the predicate p, and a2 is the array of all the elements of a that do not satisfy p. The order of the elements in the input array is preserved.

Array transformations

val rev : 'a array -> 'a array
Array reversal.
val rev_in_place : 'a array -> unit
In-place array reversal. The array argument is updated.
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 concatenates a list of arrays.
val sub : 'a array -> int -> 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.
Raises 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 -> int -> 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.
Raises Invalid_argument "Array.fill" if ofs and len do not designate a valid subarray of a.
val blit : 'a array -> int -> 'a array -> int -> 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.
Raises 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.

Conversions

val enum : 'a array -> 'a Enum.t
Returns an enumeration of the elements of an array. Behavior of the enumeration is undefined if the contents of the array changes afterwards.
val of_enum : 'a Enum.t -> 'a array
Build an array from an enumeration.
val backwards : 'a array -> 'a Enum.t
Returns an enumeration of the elements of an array, from last to first.
val of_backwards : 'a Enum.t -> 'a array
Build an array from an enumeration, going into reverse order.
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.

Utilities

val make_compare : ('a -> 'a -> int) -> 'a array -> 'a array -> int
make_compare c generates the lexicographical order on arrays induced by c
val sort : ('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 (see below for a complete specification). For example, Standard.compare is a suitable comparison function, provided there are no floating-point NaN values in the data. After calling Array.sort, the array is sorted in place in increasing order. Array.sort is guaranteed to run in constant heap space and (at most) logarithmic stack space.

The current implementation uses Heap Sort. It runs in constant stack space.

Specification of the comparison function: Let a be the array and cmp the comparison function. The following must be true for all x, y, z in a :

When Array.sort returns, a contains the same elements as before, reordered in such a way that for all i and j valid indices of a :
val stable_sort : ('a -> 'a -> int) -> 'a array -> unit
Same as Array.sort, but the sorting algorithm is stable (i.e. elements that compare equal are kept in their original order) and not guaranteed to run in constant heap space.

The current implementation uses Merge Sort. It uses n/2 words of heap space, where n is the length of the array. It is usually faster than the current implementation of Array.sort.

val fast_sort : ('a -> 'a -> int) -> 'a array -> unit
Same as Array.sort or Array.stable_sort, whichever is faster on typical input.

Boilerplate code


S-Expressions

val t_of_sexp : (Sexplib.Sexp.t -> 'a) -> Sexplib.Sexp.t -> 'a t
val sexp_of_t : ('a -> Sexplib.Sexp.t) -> 'a t -> Sexplib.Sexp.t

Printing

val print : ?first:string ->
?last:string ->
?sep:string ->
('a IO.output -> 'b -> unit) ->
'a IO.output -> 'b t -> unit
Print the contents of an array
val sprint : ?first:string ->
?last:string ->
?sep:string ->
('a IO.output -> 'b -> unit) -> 'b t -> string
Using a string printer, print an array to a string (as sprintf vs. printf)
val t_printer : 'a Value_printer.t ->
'a t Value_printer.t
module Array.Cap: sig .. end
Capabilities for arrays.

Boilerplate code


S-Expressions

val t_of_sexp : (Sexplib.Sexp.t -> 'a) -> Sexplib.Sexp.t -> 'a t
val sexp_of_t : ('a -> Sexplib.Sexp.t) -> 'a t -> Sexplib.Sexp.t

Printing

val print : ?first:string ->
?last:string ->
?sep:string ->
('a IO.output -> 'b -> unit) ->
'a IO.output -> 'b t -> unit
val sprint : ?first:string ->
?last:string ->
?sep:string ->
('a IO.output -> 'b -> unit) -> 'b t -> string
Using a string printer, print an array to a string (as sprintf vs. printf)

Override modules


The following modules replace functions defined in Array with functions behaving slightly differently but having the same name. This is by design: the functions meant to override the corresponding functions of Array.

To take advantage of these overrides, you probably want to or . For instance, to open a version of Array with exceptionless error management, you may write open Array, Exceptionless. To locally replace module Array with a module of the same name but with exceptionless error management, you may write module Array = Array include Exceptionless.

module Array.Exceptionless: sig .. end
Operations on Array without exceptions.
module Array.Labels: sig .. end
Operations on Array with labels.