Array Import and Export

Reference for converting arrays to and from other formats.

These methods allow you to convert NDArray objects to PHP native types, raw bytes, or other formats for interoperability.

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toArray()

Convert to nested PHP array matching the array shape.

public function toArray(): array|bool|float|int

Uses flat typed extraction from Rust and builds nested structure in PHP. For 0-dimensional arrays, returns a scalar.

Parameters

None.

Returns

• array<mixed>|bool|float|int - Nested array for N-dimensional arrays, scalar for 0-dimensional.

Examples

$arr = NDArray::array([[1, 2], [3, 4]]);
print_r($arr->toArray());
// Output: [[1, 2], [3, 4]]

$scalar = NDArray::array([42])->squeeze();
var_dump($scalar->toArray());  // int(42)

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toScalar()

Convert 0-dimensional array to scalar.

public function toScalar(): bool|float|int

Returns float, int, or bool depending on the array's dtype. Throws if the array is not 0-dimensional.

Parameters

None.

Returns

• bool|float|int - Single scalar value.

Examples

// 0D array from squeezing a single-element array
$arr = NDArray::array([3.14])->squeeze();
echo $arr->toScalar();  // 3.14

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toBytes()

Return raw bytes of the array/view in C-order.

public function toBytes(): string

Parameters

None.

Returns

• string - Raw binary representation of the array data.

Examples

$arr = NDArray::array([1.0, 2.0, 3.0], DType::Float64);
$bytes = $arr->toBytes();
// Length = 3 * 8 = 24 bytes for Float64

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intoBuffer()

Copy flattened C-order data into a caller-allocated C buffer.

public function intoBuffer(CData $buffer, int $start = 0, ?int $len = null): int

Parameters

Name	Type	Description
$buffer	CData	Destination typed C buffer (FFI)
$start	int	Starting element offset (0-indexed). Default: 0
$len	int|null	Number of elements to copy. Default: null (copy to end)

Returns

• int - Number of elements copied.

Examples

$arr = NDArray::array([1.0, 2.0, 3.0, 4.0, 5.0]);
$ffi = \PhpMlKit\NDArray\FFI\Lib::get();
$buffer = $ffi->new('double[5]');

// Copy all elements
$n = $arr->intoBuffer($buffer);
// $n === 5

// Copy from offset
$buffer = $ffi->new('double[3]');
$n = $arr->intoBuffer($buffer, 2);  // Start at index 2
// $n === 3 (elements 2, 3, 4)

// Copy with explicit length
$buffer = $ffi->new('double[2]');
$n = $arr->intoBuffer($buffer, 1, 2);  // Start at 1, copy 2 elements
// $n === 2 (elements 1, 2)

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Summary Table

Method	Output Format	Use Case
toArray()	Nested PHP array	Export to PHP code
toScalar()	Single value	Extract 0D array value
toBytes()	Binary string	Binary serialization
intoBuffer()	FFI C buffer	Low-level FFI interop

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Next Steps

• Array Creation - Converting from PHP arrays
• NDArray Class - Array properties and metadata