(guile.info.gz) Uniform Arrays
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22.6.3 Uniform Arrays
---------------------
"Uniform arrays" have elements all of the same type and occupy less
storage than conventional arrays. Uniform arrays with a single
zero-based dimension are also known as "uniform vectors". The
procedures in this section can also be used on conventional arrays,
vectors, bit-vectors and strings.
When creating a uniform array, the type of data to be stored is
indicated with a PROTOTYPE argument. The following table lists the
types available and example prototypes:
prototype type printing character
#t boolean (bit-vector) b
#\a char (string) a
#\nul byte (integer) y
's short (integer) h
1 unsigned long (integer) u
-1 signed long (integer) e
'l signed long long (integer) l
1.0 float (single precision) s
1/3 double (double precision float) i
0+i complex (double precision) c
() conventional vector
Unshared uniform arrays of characters with a single zero-based dimension
are identical to strings:
(make-uniform-array #\a 3) =>
"aaa"
Unshared uniform arrays of booleans with a single zero-based dimension
are identical to bit-vectors Bit Vectors.
(make-uniform-array #t 3) =>
#*111
Other uniform vectors are written in a form similar to that of vectors,
except that a single character from the above table is put between `#'
and `('. For example, a uniform vector of signed long integers is
displayed in the form `'#e(3 5 9)'.
-- Scheme Procedure: array? 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
elsewhere.
-- Scheme Procedure: make-uniform-array prototype bound1 bound2 ...
Create and return a uniform array of type corresponding to
PROTOTYPE that has as many dimensions as there are BOUNDs and fill
it with PROTOTYPE.
-- Scheme Procedure: array-prototype ra
-- C Function: scm_array_prototype (ra)
Return an object that would produce an array of the same type as
ARRAY, if used as the PROTOTYPE for `make-uniform-array'.
-- Scheme Procedure: list->uniform-array ndim prot lst
-- Scheme Procedure: list->uniform-vector prot lst
-- C Function: scm_list_to_uniform_array (ndim, prot, lst)
Return a uniform array of the type indicated by prototype PROT
with elements the same as those of LST. Elements must be of the
appropriate type, no coercions are done.
-- Scheme Procedure: uniform-vector-fill! uve fill
Store FILL in every element of UVE. The value returned is
unspecified.
-- Scheme Procedure: uniform-vector-length v
-- C Function: scm_uniform_vector_length (v)
Return the number of elements in UVE.
-- Scheme Procedure: dimensions->uniform-array dims prot [fill]
-- Scheme Procedure: make-uniform-vector length prototype [fill]
-- C Function: scm_dimensions_to_uniform_array (dims, prot, fill)
Create and return a uniform array or vector of type corresponding
to PROTOTYPE with dimensions DIMS or length LENGTH. If FILL is
supplied, it's used to fill the array, otherwise PROTOTYPE is used.
-- Scheme Procedure: uniform-array-read! ra [port_or_fd [start [end]]]
-- Scheme Procedure: uniform-vector-read! uve [port-or-fdes] [start]
[end]
-- C Function: scm_uniform_array_read_x (ra, port_or_fd, start, end)
Attempt to read all elements of URA, in lexicographic order, as
binary objects from PORT-OR-FDES. If an end of file is
encountered, the objects up to that point are put into URA
(starting at the beginning) and the remainder of the array is
unchanged.
The optional arguments START and END allow a specified region of a
vector (or linearized array) to be read, leaving the remainder of
the vector unchanged.
`uniform-array-read!' returns the number of objects read.
PORT-OR-FDES may be omitted, in which case it defaults to the value
returned by `(current-input-port)'.
-- Scheme Procedure: uniform-array-write v [port_or_fd [start [end]]]
-- Scheme Procedure: uniform-vector-write uve [port-or-fdes] [start]
[end]
-- C Function: scm_uniform_array_write (v, port_or_fd, start, end)
Writes all elements of URA as binary objects to PORT-OR-FDES.
The optional arguments START and END allow a specified region of a
vector (or linearized array) to be written.
The number of objects actually written is returned. PORT-OR-FDES
may be omitted, in which case it defaults to the value returned by
`(current-output-port)'.
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