saveArray

Save an array to a binary file. More...

Functions
AFAPI int	saveArray (const char *key, const array &arr, const char *filename, const bool append=false)
AFAPI af_err	af_save_array (int *index, const char *key, const af_array arr, const char *filename, const bool append)

Detailed Description

Save an array to a binary file.

The saveArray and readArray functions are designed to provide store and read access to arrays using files written to disk.

The format of the file (version 1) is as follows:

Header:

Description	Data Type	Size (Bytes)	Detailed Desc
Version	Char	1	ArrayFire File Format Version for future use. Currently set to 1
Array Count	Int	4	No. of Arrays stored in file

Per Array:

Description	Data Type	Size (Bytes)	Detailed Desc
Length of Key String	Int	4	No. of characters (excluding null ending) in the key string
Key	Char []	length	Key of the Array. Used when reading from file
Offset	Int64	8	No of bytes between offset and start of next array
Array Type	Char	1	Type corresponding to af_dtype enum
Dims (4 values)	Int64	4 * 8 = 32	Dimensions of the Array
Data	Type	sizeof(Type) * dims.elements()	Actual data of the array

The offset is equal to 1 byte (type) + 32 bytes (dims) + size of data.

An file with 2 arrays would look like (representative)

‍1
2
Array 1 Key Length
Array 1 Key
Array 1 Offset
Array 1 Type
Array 1 Dims
Array 1 Data
Array 2 Key Length
Array 2 Key
Array 2 Offset
Array 2 Type
Array 2 Dims
Array 2 Data

Save array allows you to append any number of Arrays to the same file using the append argument. If the append argument is false, then the contents of the file are discarded and new array is written anew.

On each append, the array counter in the header is incremented and the new array is written to the end of the file. This function does not check if the tag is unique or not.

Function Documentation

af_save_array()

AFAPI af_err af_save_array	(	int *	index,
		const char *	key,
		const af_array	arr,
		const char *	filename,
		const bool	append
	)

Parameters

[out]	index	is the index location of the array in the file
[in]	key	is an expression used as tag/key for the array during af::readArray()
[in]	arr	is the array to be written
[in]	filename	is the path to the location on disk
[in]	append	is used to append to an existing file when true and create or overwrite an existing file when false

saveArray()

AFAPI int saveArray	(	const char *	key,
		const array &	arr,
		const char *	filename,
		const bool	append = false
	)

Parameters

[in]	key	is an expression used as tag/key for the array during readArray
[in]	arr	is the array to be written
[in]	filename	is the path to the location on disk
[in]	append	is used to append to an existing file when true and create or overwrite an existing file when false

Returns

index of the saved array in the file