module Genarray:sig
..end
type ('a, 'b, 'c)
t
Genarray.t
is the type of big arrays with variable
numbers of dimensions. Any number of dimensions between 1 and 16
is supported.
The three type parameters to Genarray.t
identify the array element
kind and layout, as follows:
'a
, is the OCaml type for accessing array
elements (float
, int
, int32
, int64
, nativeint
);'b
, is the actual kind of array elements
(float32_elt
, float64_elt
, int8_signed_elt
, int8_unsigned_elt
,
etc);'c
, identifies the array layout
(c_layout
or fortran_layout
).(float, float32_elt, fortran_layout) Genarray.t
is the type of generic big arrays containing 32-bit floats
in Fortran layout; reads and writes in this array use the
OCaml type float
.val create : ('a, 'b) Bigarray.kind ->
'c Bigarray.layout -> int array -> ('a, 'b, 'c) t
Genarray.create kind layout dimensions
returns a new big array
whose element kind is determined by the parameter kind
(one of
float32
, float64
, int8_signed
, etc) and whose layout is
determined by the parameter layout
(one of c_layout
or
fortran_layout
). The dimensions
parameter is an array of
integers that indicate the size of the big array in each dimension.
The length of dimensions
determines the number of dimensions
of the bigarray.
For instance, Genarray.create int32 c_layout [|4;6;8|]
returns a fresh big array of 32-bit integers, in C layout,
having three dimensions, the three dimensions being 4, 6 and 8
respectively.
Big arrays returned by Genarray.create
are not initialized:
the initial values of array elements is unspecified.
Genarray.create
raises Invalid_argument
if the number of dimensions
is not in the range 1 to 16 inclusive, or if one of the dimensions
is negative.
val num_dims : ('a, 'b, 'c) t -> int
val dims : ('a, 'b, 'c) t -> int array
Genarray.dims a
returns all dimensions of the big array a
,
as an array of integers of length Genarray.num_dims a
.val nth_dim : ('a, 'b, 'c) t -> int -> int
Genarray.nth_dim a n
returns the n
-th dimension of the
big array a
. The first dimension corresponds to n = 0
;
the second dimension corresponds to n = 1
; the last dimension,
to n = Genarray.num_dims a - 1
.
Raise Invalid_argument
if n
is less than 0 or greater or equal than
Genarray.num_dims a
.val kind : ('a, 'b, 'c) t -> ('a, 'b) Bigarray.kind
val layout : ('a, 'b, 'c) t -> 'c Bigarray.layout
val size_in_bytes : ('a, 'b, 'c) t -> int
val get : ('a, 'b, 'c) t -> int array -> 'a
Genarray.get a [|i1; ...; iN|]
returns the element of a
whose coordinates are i1
in the first dimension, i2
in
the second dimension, ..., iN
in the N
-th dimension.
If a
has C layout, the coordinates must be greater or equal than 0
and strictly less than the corresponding dimensions of a
.
If a
has Fortran layout, the coordinates must be greater or equal
than 1 and less or equal than the corresponding dimensions of a
.
Raise Invalid_argument
if the array a
does not have exactly N
dimensions, or if the coordinates are outside the array bounds.
If N > 3
, alternate syntax is provided: you can write
a.{i1, i2, ..., iN}
instead of Genarray.get a [|i1; ...; iN|]
.
(The syntax a.{...}
with one, two or three coordinates is
reserved for accessing one-, two- and three-dimensional arrays
as described below.)
val set : ('a, 'b, 'c) t -> int array -> 'a -> unit
Genarray.set a [|i1; ...; iN|] v
stores the value v
in the
element of a
whose coordinates are i1
in the first dimension,
i2
in the second dimension, ..., iN
in the N
-th dimension.
The array a
must have exactly N
dimensions, and all coordinates
must lie inside the array bounds, as described for Genarray.get
;
otherwise, Invalid_argument
is raised.
If N > 3
, alternate syntax is provided: you can write
a.{i1, i2, ..., iN} <- v
instead of
Genarray.set a [|i1; ...; iN|] v
.
(The syntax a.{...} <- v
with one, two or three coordinates is
reserved for updating one-, two- and three-dimensional arrays
as described below.)
val sub_left : ('a, 'b, Bigarray.c_layout) t ->
int -> int -> ('a, 'b, Bigarray.c_layout) t
Genarray.sub_left a ofs len
returns a big array with the same number of dimensions as a
,
and the same dimensions as a
, except the first dimension,
which corresponds to the interval [ofs ... ofs + len - 1]
of the first dimension of a
. No copying of elements is
involved: the sub-array and the original array share the same
storage space. In other terms, the element at coordinates
[|i1; ...; iN|]
of the sub-array is identical to the
element at coordinates [|i1+ofs; ...; iN|]
of the original
array a
.
Genarray.sub_left
applies only to big arrays in C layout.
Raise Invalid_argument
if ofs
and len
do not designate
a valid sub-array of a
, that is, if ofs < 0
, or len < 0
,
or ofs + len > Genarray.nth_dim a 0
.
val sub_right : ('a, 'b, Bigarray.fortran_layout) t ->
int -> int -> ('a, 'b, Bigarray.fortran_layout) t
Genarray.sub_right a ofs len
returns a big array with the same number of dimensions as a
,
and the same dimensions as a
, except the last dimension,
which corresponds to the interval [ofs ... ofs + len - 1]
of the last dimension of a
. No copying of elements is
involved: the sub-array and the original array share the same
storage space. In other terms, the element at coordinates
[|i1; ...; iN|]
of the sub-array is identical to the
element at coordinates [|i1; ...; iN+ofs|]
of the original
array a
.
Genarray.sub_right
applies only to big arrays in Fortran layout.
Raise Invalid_argument
if ofs
and len
do not designate
a valid sub-array of a
, that is, if ofs < 1
, or len < 0
,
or ofs + len > Genarray.nth_dim a (Genarray.num_dims a - 1)
.
val slice_left : ('a, 'b, Bigarray.c_layout) t ->
int array -> ('a, 'b, Bigarray.c_layout) t
Genarray.slice_left a [|i1; ... ; iM|]
returns the 'slice'
of a
obtained by setting the first M
coordinates to
i1
, ..., iM
. If a
has N
dimensions, the slice has
dimension N - M
, and the element at coordinates
[|j1; ...; j(N-M)|]
in the slice is identical to the element
at coordinates [|i1; ...; iM; j1; ...; j(N-M)|]
in the original
array a
. No copying of elements is involved: the slice and
the original array share the same storage space.
Genarray.slice_left
applies only to big arrays in C layout.
Raise Invalid_argument
if M >= N
, or if [|i1; ... ; iM|]
is outside the bounds of a
.
val slice_right : ('a, 'b, Bigarray.fortran_layout) t ->
int array -> ('a, 'b, Bigarray.fortran_layout) t
Genarray.slice_right a [|i1; ... ; iM|]
returns the 'slice'
of a
obtained by setting the last M
coordinates to
i1
, ..., iM
. If a
has N
dimensions, the slice has
dimension N - M
, and the element at coordinates
[|j1; ...; j(N-M)|]
in the slice is identical to the element
at coordinates [|j1; ...; j(N-M); i1; ...; iM|]
in the original
array a
. No copying of elements is involved: the slice and
the original array share the same storage space.
Genarray.slice_right
applies only to big arrays in Fortran layout.
Raise Invalid_argument
if M >= N
, or if [|i1; ... ; iM|]
is outside the bounds of a
.
val blit : ('a, 'b, 'c) t -> ('a, 'b, 'c) t -> unit
Genarray.blit src dst
copies all elements of src
into
dst
. Both arrays src
and dst
must have the same number of
dimensions and equal dimensions. Copying a sub-array of src
to a sub-array of dst
can be achieved by applying Genarray.blit
to sub-array or slices of src
and dst
.val fill : ('a, 'b, 'c) t -> 'a -> unit
Genarray.fill a v
stores the value v
in all elements of
the big array a
. Setting only some elements of a
to v
can be achieved by applying Genarray.fill
to a sub-array
or a slice of a
.val map_file : Unix.file_descr ->
?pos:int64 ->
('a, 'b) Bigarray.kind ->
'c Bigarray.layout -> bool -> int array -> ('a, 'b, 'c) t
Genarray.map_file fd kind layout shared dims
returns a big array of kind kind
, layout layout
,
and dimensions as specified in dims
. The data contained in
this big array are the contents of the file referred to by
the file descriptor fd
(as opened previously with
Unix.openfile
, for example). The optional pos
parameter
is the byte offset in the file of the data being mapped;
it defaults to 0 (map from the beginning of the file).
If shared
is true
, all modifications performed on the array
are reflected in the file. This requires that fd
be opened
with write permissions. If shared
is false
, modifications
performed on the array are done in memory only, using
copy-on-write of the modified pages; the underlying file is not
affected.
Genarray.map_file
is much more efficient than reading
the whole file in a big array, modifying that big array,
and writing it afterwards.
To adjust automatically the dimensions of the big array to
the actual size of the file, the major dimension (that is,
the first dimension for an array with C layout, and the last
dimension for an array with Fortran layout) can be given as
-1
. Genarray.map_file
then determines the major dimension
from the size of the file. The file must contain an integral
number of sub-arrays as determined by the non-major dimensions,
otherwise Failure
is raised.
If all dimensions of the big array are given, the file size is
matched against the size of the big array. If the file is larger
than the big array, only the initial portion of the file is
mapped to the big array. If the file is smaller than the big
array, the file is automatically grown to the size of the big array.
This requires write permissions on fd
.
Array accesses are bounds-checked, but the bounds are determined by
the initial call to map_file
. Therefore, you should make sure no
other process modifies the mapped file while you're accessing it,
or a SIGBUS signal may be raised. This happens, for instance, if the
file is shrunk.
Sys_error
in the case of any errors from the
underlying system calls. Invalid_argument
or Failure
may be
raised in cases where argument validation fails.