dlite-arrays

dlite-arrays#

Simple API for accessing the data of multidimensional array properties.

The DLiteArray structure adds some basic functionality for accessing multidimensional array data. It it not a complete array library and do no memory management. It is neither optimised for speed, so don’t use it for writing optimised solvers.

Included features:

indexing
iteration
comparisons
reshaping
slicing
transpose
make_continuous
pretty printing

Typedefs

typedef struct _DLiteArray DLiteArray#: DLite n-dimensional arrays

typedef struct _DLiteArrayIter DLiteArrayIter#: Array iterator object.

Functions

DLiteArray *dlite_array_create(void *data, DLiteType type, size_t size, int ndims, const size_t *shape)#

Creates a new array object.

data is a pointer to array data. No copy is done. type is the type of each element. size is the size of each element. ndims is the number of dimensions. shape is the size of each dimensions. Length: ndims.

Returns the new array or NULL on error.

DLiteArray *dlite_array_create_order(void *data, DLiteType type, size_t size, int ndims, const size_t *shape, int order)#: Like dlite_array_create(), but with argument order, which can have the values: ‘C’: row-major (C-style) order, no reordering. ‘F’: coloumn-major (Fortran-style) order, transposed order.

void dlite_array_free(DLiteArray *arr)#: Free an array object, but not the associated data.

size_t dlite_array_size(const DLiteArray *arr)#: Returns the memory size in bytes of array arr.

int dlite_array_is_continuous(const DLiteArray *arr)#: Returns non-zero if array arr describes a C-continuous memory layout.

void *dlite_array_index(const DLiteArray *arr, int *ind)#: Returns a pointer to data at index ind, where ind is an array of length arr->ndims.

int dlite_array_iter_init(DLiteArrayIter *iter, const DLiteArray *arr)#

Initialise array iterator object iter, for iteration over array arr.

Returns non-zero on error.

void dlite_array_iter_deinit(DLiteArrayIter *iter)#: Deinitialise array iterator object iter.

void *dlite_array_iter_next(DLiteArrayIter *iter)#: Returns the next element of from array iterator, or NULL if all elements has been visited.

int dlite_array_compare(const DLiteArray *a, const DLiteArray *b)#: Returns 1 is arrays a and b are equal, zero otherwise.

DLiteArray *dlite_array_slice(const DLiteArray *arr, int *start, int *stop, int *step)#

Returns a new array object representing a slice of arr. start, stop and step has the same meaning as in Python and should be either NULL or arrays of length arr->ndims.

For step[n] > 0 the range for dimension n is increasing (assuming step[n]=1):

start[n], start[n]+1, ... stop[n]-2, stop[n]-1

For step[n] < 0 the range for dimension n is decreasing: (assuming step[n]=1):

start[n]-1, start[n]-2, ... stop[n]+1, stop[n]

Like Python, negative values of start or stop counts from the back. Hence index -k is equivalent to arr->shape[n]-|k|.

If start is NULL, it will default to zero for dimensions n with positive step and arr->shape[n] for dimensions with negative step.

If stop is NULL, it will default to arr->shape[n] for dimensions n with positive step and zero for dimensions with negative step.

If step is NULL, it defaults to one.

Returns NULL on error.

Note

The above behavior is not fully consistent with Python for negative step sizes. While the range for negative steps in dlite is given above, Python returns the following range:

start[n], start[n]-1, ... stop[n]+2, stop[n]+1

In Python, you can get the full reversed range by specifying None as the stop value. But None is not a valid C integer. In dlite you can get the full reversed range by setting stop[n] to zero.

DLiteArray *dlite_array_reshape(const DLiteArray *arr, int ndims, const size_t *shape)#

Returns a new array object representing arr with a new shape specified with ndims and shape. shape should be compatible with the old shape. The current implementation also requires that arr is C-continuous.

Returns NULL on error.

DLiteArray *dlite_array_transpose(DLiteArray *arr)#

Returns a new array object corresponding to the transpose of arr (that is, an array with reversed order of dimensions).

Returns NULL on error.

Note

This function does not change the underlying data. If you want to convert between C and Fortran array layout, you should call dlite_make_continuous() on the array object returned by this function.

void *dlite_array_make_continuous(DLiteArray *arr)#

Creates a continuous copy of the data for arr (using malloc()) and updates arr.

Returns a the new copy of the data or NULL on error.

int dlite_array_printf(FILE *fp, const DLiteArray *arr, int width, int prec)#

Print array arr to stream fp.

The width and prec arguments corresponds to the printf() minimum field width and precision/length modifier. If you set them to -1, a suitable value will selected according to type. To ignore their effect, set width to zero or prec to -2.

Returns non-zero on error.

struct _DLiteArray#

#include <dlite-arrays.h>

DLite n-dimensional arrays

Public Members

void *data#: pointer to array data

DLiteType type#: data type of elements

size_t size#: size of each element in bytes

int ndims#: number of dimensions

size_t *shape#: dimension sizes [ndims]

int *strides#: strides, that is number of bytes between two following elements along each dimension [ndims] Note: strides can be negative, so we must use a signed type.

struct _DLiteArrayIter#

#include <dlite-arrays.h>

Array iterator object.

Public Members

const DLiteArray *arr#: pointer to the array we are iterating over

int *ind#: the current index

dlite-arrays

Contents

dlite-arrays#