Printing NDArrays

Controlling how arrays are displayed when used as strings.

NDArray implements PHP's Stringable interface, meaning you can use arrays directly in any context that expects a string—echo, print, string concatenation, or functions like sprintf().

Basic Usage

The simplest way to see an array's contents:

$arr = NDArray::array([1, 2, 3, 4, 5]);
echo $arr;

Output:

array(5)
[1 2 3 4 5]

Every array display includes a header showing its shape, followed by the actual data.

Echo and Print

$arr = NDArray::array([[1, 2], [3, 4]]);

echo $arr;
print $arr;

Both echo and print produce the same output. The array header shows dimensions clearly:

array(2, 2)
[
 [1 2]
 [3 4]
]

String Interpolation

Use arrays in string contexts:

$arr = NDArray::array([10, 20, 30]);

// Direct interpolation
echo "Values: $arr";
// Values: array(3)
// [10 20 30]

// With sprintf
$output = sprintf("The array contains: %s", $arr);
// "The array contains: array(3)\n[10 20 30]"

String Concatenation

$a = NDArray::array([1, 2]);
$b = NDArray::array([3, 4]);

$result = "First: " . $a . "\nSecond: " . $b;
echo $result;

Output:

First: array(2)
[1 2]
Second: array(2)
[3 4]

Output by Dimension

The display format adapts based on the number of dimensions.

0D Arrays (Scalars)

$scalar = NDArray::array(42);
echo $scalar;

Output:

array(0)
42

1D Arrays

$vec = NDArray::array([1, 2, 3, 4, 5]);
echo $vec;

Output:

array(5)
[1 2 3 4 5]

2D Arrays

$matrix = NDArray::array([
    [1, 2, 3],
    [4, 5, 6]
]);
echo $matrix;

Output:

array(2, 3)
[
 [1 2 3]
 [4 5 6]
]

3D Arrays

$tensor = NDArray::array([
    [[1, 2], [3, 4]],
    [[5, 6], [7, 8]]
]);
echo $tensor;

Output:

array(2, 2, 2)
[
  [1 2]
  [3 4]

  [5 6]
  [7 8]
]

4D and Higher

Higher-dimensional arrays display with nested brackets:

$data = NDArray::random([2, 2, 3, 4]);
echo $data;

Output:

array(2, 2, 3, 4)
[
  [
    [
      [0.123 0.456 0.789 0.234]
      [0.567 0.890 0.123 0.456]
      [0.789 0.234 0.567 0.890]]

    [
      [0.901 0.234 0.567 0.890]
      [0.123 0.456 0.789 0.234]
      [0.456 0.789 0.901 0.123]
    ]
  ]

  [
    [
      [0.234 0.567 0.890 0.123]
      [0.456 0.789 0.234 0.567]
      [0.890 0.123 0.456 0.789]]

    [
      [0.789 0.234 0.567 0.890]
      [0.123 0.456 0.789 0.234]
      [0.567 0.890 0.123 0.456]
    ]
  ]
]

Print Options

Control array formatting globally using print options. These settings affect all subsequent array displays in your application.

setPrintOptions()

Configure how arrays are displayed:

NDArray::setPrintOptions(
    threshold: 1000,  // Max elements before truncation
    edgeitems: 3,      // Items to show at edges when truncating
    precision: 8       // Decimal places for floats
);

Parameters:

• threshold - Maximum number of elements before array is truncated. Default: 1000
• edgeitems - Number of items to show at each edge when truncating. Default: 3
• precision - Number of decimal places for floating-point numbers. Default: 8

getPrintOptions()

Retrieve current print settings:

$options = NDArray::getPrintOptions();
print_r($options);
// [
//     'threshold' => 1000,
//     'edgeitems' => 3,
//     'precision' => 8
// ]

resetPrintOptions()

Restore defaults:

NDArray::resetPrintOptions();
// Now uses: threshold=1000, edgeitems=3, precision=8

Next Steps

• Operations - Learn about array computations
• Indexing and Slicing - Access array elements
• API Reference - Complete method documentation