(guile.info.gz) Conventional Arrays
(guile.info.gz) Array Mapping
22.6.1 Conventional Arrays
"Conventional arrays" are a collection of cells organized into an
arbitrary number of dimensions. Each cell can hold any kind of Scheme
value and can be accessed in constant time by supplying an index for
each dimension. This contrasts with uniform arrays, which use memory
more efficiently but can hold data of only a single type, and lists
where inserting and deleting cells is more efficient, but more time is
usually required to access a particular cell.
A conventional array is displayed as `#' followed by the "rank"
(number of dimensions) followed by the cells, organized into dimensions
using parentheses. The nesting depth of the parentheses is equal to
When an array is created, the number of dimensions and range of each
dimension must be specified, e.g., to create a 2x3 array with a
(make-array 'ho 2 3) =>
#2((ho ho ho) (ho ho ho))
The range of each dimension can also be given explicitly, e.g.,
another way to create the same array:
(make-array 'ho '(0 1) '(0 2)) =>
#2((ho ho ho) (ho ho ho))
A conventional array with one dimension based at zero is identical to
(make-array 'ho 3) =>
#(ho ho ho)
The following procedures can be used with conventional arrays (or
-- Scheme Procedure: array? v [prot]
-- C Function: scm_array_p (v, prot)
Return `#t' if the OBJ is an array, and `#f' if not. The
PROTOTYPE argument is used with uniform arrays and is described
-- Scheme Procedure: make-array initial-value bound1 bound2 ...
Create and return an array that has as many dimensions as there are
BOUNDs and fill it with INITIAL-VALUE. Each BOUND may be a
positive non-zero integer N, in which case the index for that
dimension can range from 0 through N-1; or an explicit index range
specifier in the form `(LOWER UPPER)', where both LOWER and UPPER
are integers, possibly less than zero, and possibly the same
number (however, LOWER cannot be greater than UPPER).
-- Scheme Procedure: uniform-vector-ref v args
-- Scheme Procedure: array-ref v . args
-- C Function: scm_uniform_vector_ref (v, args)
Return the element at the `(index1, index2)' element in ARRAY.
-- Scheme Procedure: array-in-bounds? v . args
-- C Function: scm_array_in_bounds_p (v, args)
Return `#t' if its arguments would be acceptable to `array-ref'.
-- Scheme Procedure: array-set! v obj . args
-- Scheme Procedure: uniform-array-set1! v obj args
-- C Function: scm_array_set_x (v, obj, args)
Set the element at the `(index1, index2)' element in ARRAY to
NEW-VALUE. The value returned by array-set! is unspecified.
-- Scheme Procedure: make-shared-array oldra mapfunc . dims
-- C Function: scm_make_shared_array (oldra, mapfunc, dims)
`make-shared-array' can be used to create shared subarrays of other
arrays. The MAPPER is a function that translates coordinates in
the new array into coordinates in the old array. A MAPPER must be
linear, and its range must stay within the bounds of the old
array, but it can be otherwise arbitrary. A simple example:
(define fred (make-array #f 8 8))
(make-shared-array fred (lambda (i) (list i i)) 8))
(array-set! freds-diagonal 'foo 3)
(array-ref fred 3 3) => foo
(make-shared-array fred (lambda (i j) (list (+ 3 i) (+ 3 j))) 2 2))
(array-ref freds-center 0 0) => foo
-- Scheme Procedure: shared-array-increments ra
-- C Function: scm_shared_array_increments (ra)
For each dimension, return the distance between elements in the
-- Scheme Procedure: shared-array-offset ra
-- C Function: scm_shared_array_offset (ra)
Return the root vector index of the first element in the array.
-- Scheme Procedure: shared-array-root ra
-- C Function: scm_shared_array_root (ra)
Return the root vector of a shared array.
-- Scheme Procedure: transpose-array ra . args
-- C Function: scm_transpose_array (ra, args)
Return an array sharing contents with ARRAY, but with dimensions
arranged in a different order. There must be one DIM argument for
each dimension of ARRAY. DIM0, DIM1, ... should be integers
between 0 and the rank of the array to be returned. Each integer
in that range must appear at least once in the argument list.
The values of DIM0, DIM1, ... correspond to dimensions in the
array to be returned, their positions in the argument list to
dimensions of ARRAY. Several DIMs may have the same value, in
which case the returned array will have smaller rank than ARRAY.
(transpose-array '#2((a b) (c d)) 1 0) => #2((a c) (b d))
(transpose-array '#2((a b) (c d)) 0 0) => #1(a d)
(transpose-array '#3(((a b c) (d e f)) ((1 2 3) (4 5 6))) 1 1 0) =>
#2((a 4) (b 5) (c 6))
-- Scheme Procedure: enclose-array ra . axes
-- C Function: scm_enclose_array (ra, axes)
DIM0, DIM1 ... should be nonnegative integers less than the rank
of ARRAY. ENCLOSE-ARRAY returns an array resembling an array of
shared arrays. The dimensions of each shared array are the same
as the DIMth dimensions of the original array, the dimensions of
the outer array are the same as those of the original array that
did not match a DIM.
An enclosed array is not a general Scheme array. Its elements may
not be set using `array-set!'. Two references to the same element
of an enclosed array will be `equal?' but will not in general be
`eq?'. The value returned by ARRAY-PROTOTYPE when given an
enclosed array is unspecified.
(enclose-array '#3(((a b c) (d e f)) ((1 2 3) (4 5 6))) 1) =>
#<enclosed-array (#1(a d) #1(b e) #1(c f)) (#1(1 4) #1(2 5) #1(3 6))>
(enclose-array '#3(((a b c) (d e f)) ((1 2 3) (4 5 6))) 1 0) =>
#<enclosed-array #2((a 1) (d 4)) #2((b 2) (e 5)) #2((c 3) (f 6))>
-- Scheme Procedure: array-shape array
Return a list of inclusive bounds of integers.
(array-shape (make-array 'foo '(-1 3) 5)) => ((-1 3) (0 4))
-- Scheme Procedure: array-dimensions ra
-- C Function: scm_array_dimensions (ra)
`Array-dimensions' is similar to `array-shape' but replaces
elements with a `0' minimum with one greater than the maximum. So:
(array-dimensions (make-array 'foo '(-1 3) 5)) => ((-1 3) 5)
-- Scheme Procedure: array-rank ra
-- C Function: scm_array_rank (ra)
Return the number of dimensions of OBJ. If OBJ is not an array,
`0' is returned.
-- Scheme Procedure: array->list v
-- C Function: scm_array_to_list (v)
Return a list consisting of all the elements, in order, of ARRAY.
-- Scheme Procedure: array-copy! src dst
-- Scheme Procedure: array-copy-in-order! src dst
-- C Function: scm_array_copy_x (src, dst)
Copy every element from vector or array SOURCE to the
corresponding element of DESTINATION. DESTINATION must have the
same rank as SOURCE, and be at least as large in each dimension.
The order is unspecified.
-- Scheme Procedure: array-fill! ra fill
-- C Function: scm_array_fill_x (ra, fill)
Store FILL in every element of ARRAY. The value returned is
-- Scheme Procedure: array-equal? ra0 ra1
Return `#t' iff all arguments are arrays with the same shape, the
same type, and have corresponding elements which are either
`equal?' or `array-equal?'. This function differs from `equal?'
in that a one dimensional shared array may be ARRAY-EQUAL? but not
EQUAL? to a vector or uniform vector.
-- Scheme Procedure: array-contents array [strict]
-- C Function: scm_array_contents (array, strict)
If ARRAY may be "unrolled" into a one dimensional shared array
without changing their order (last subscript changing fastest),
then `array-contents' returns that shared array, otherwise it
returns `#f'. All arrays made by MAKE-ARRAY and
MAKE-UNIFORM-ARRAY may be unrolled, some arrays made by
MAKE-SHARED-ARRAY may not be.
If the optional argument STRICT is provided, a shared array will
be returned only if its elements are stored internally contiguous
(guile.info.gz) Array Mapping
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