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Pretty Pprint

Callable pretty-printer for PHP arrays with Python-like formatting. PrettyPrint is a small, zero-dependency PHP utility that formats arrays in a clean, readable, PyTorch-inspired style. It supports aligned 2D tables, 3D tensors, summarized tensor views, and flexible output options – making it ideal for ML experiments, debugging, logging, and educational projects.

Installation

Usage

Note: When used in web (non-CLI) environments, output is automatically wrapped in <pre> to preserve spacing. In CLI, no wrapping is applied. When you request a string to be returned (see return option), no auto-wrapping is applied.

Import functions

All examples below assume you have imported the helper functions from the Apphp\PrettyPrint namespace, for example:

or simply

Global helper functions

Print scalars/strings

Print 1D arrays

Compare two arrays with a difference matrix

Compare two arrays by printing both matrices (stacked) with colored cells

Label + 2D matrix

2D tensor-style formatting

Custom label instead of "tensor"

2D tensor-style formatting with summarization

3D tensor with head/tail blocks (PyTorch-like)

Select specific rows/columns

Print numeric-only column summaries

Postfix and prefix control

Return the formatted string instead of printing

Print and then exit the script

As an object

Objects with asArray() / toArray()

If you pass an object that exposes an asArray() or toArray() method, pprint / PrettyPrint will automatically convert it to an array before formatting:

If asArray() is not present but toArray() is, toArray() will be used instead.

Associative rows and strings in arrays/tensors

• Associative rows are normalized to positional values in 2D/3D formatting.
• String cells inside arrays/tensors are always printed with quotes (for example, 'engaged').
• Top-level scalar strings are unchanged and remain unquoted.

Running tests

Notes:

• Coverage drivers: You need Xdebug (xdebug.mode=coverage) or PCOV enabled for coverage reports. Without a driver, PHPUnit will warn and exit non‑zero.
• You can also run PHPUnit directly: vendor/bin/phpunit.

Benchmark

A CLI benchmark script is available at benchmarks/benchmark.php for measuring matrix build/format time and peak memory usage.

Examples:

Notes:

• Presets: small, 10k, 100k, 1m.
• Use --dry-run for huge shapes to avoid OOM.
• The script skips materialization if total cells exceed --max-cells.

Options reference

• start: string. Prefix printed before the content. Example: pprint('Hello', ['start' => "\t"]).
• end: string. Line terminator, default is double lines. Example: pprint('no newline', ['end' => '']);
• sep: string. Separator between multiple default-formatted arguments. Default is a new line. Examples: pprint('A','B','C', sep: ', ', end: '') or pprint('X','Y', ['sep' => "\n", 'end' => '']).
• label: string. Prefix label for 2D/3D formatted arrays, default array. Example: pprint($m, ['label' => 'arr']).
• precision: int. Number of digits after the decimal point for floats. Example: pprint(3.14159, precision: 2) prints 3.14.
• short: bool. When true, trims trailing float zeros and final dot (for example 1.0000 -> 1, 2.5000 -> 2.5). Default is false.
• return: bool. When true, do not echo; return the formatted string instead (no <pre> wrapping in web context). Example: $s = pprint($m, return: true);.
• headB / tailB: ints. Number of head/tail 2D blocks shown for 3D tensors.
• headRows / tailRows: ints. Rows shown per 2D slice with ellipsis between.
• headCols / tailCols: ints. Columns shown per 2D slice with ellipsis between.
• colsSummary: bool. Adds a final per-column summary row for displayed columns in 2D/3D output; only int/float values are summed.
• colsSummaryLabel: string. Visual label printed above the colsSummary summary row. Default is ---totals---.
• rowsSummary: bool. Adds an extra trailing per-row summary column in 2D/3D output; only int/float values are summed.
• rowsSummaryLabel: string. Visual label printed in the first row for the rowsSummary summary column. Default is ---totals---.
• rowsOnly / colsOnly: int or string. Limit visible rows/columns.
  • Single index: 3 or '3'.
  • Range: '2-4' (inclusive).
  • Sparse mix: '1-2,5,9-11' → indices 1,2,5,9,10,11. Applied to 2D arrays and to each 2D slice of 3D tensors.

All options can be passed as:

• trailing array: pprint($m, ['headRows' => 1, ...])
• named args (PHP 8+): $pp($m, headRows: 1, ...)

Defaults

• label: tensor
• sep: ' '
• precision: 4
• short: false
• colsSummaryLabel: ---totals---
• rowsSummaryLabel: ---totals---
• headB / tailB: 5
• headRows / tailRows: 5
• headCols / tailCols: 5

Limits

• precision: max 10
• headB / tailB / headRows / tailRows / headCols / tailCols: max 50
• label: max length 50 characters (longer labels are truncated)
• positional args (MAX_ARGS): up to 32 positional args are accepted; extras are ignored.

Positional policy:

• First arg can be a string label, number, or array.
• Exactly two positional args are allowed only for string label, array.
• Named/trailing options are applied only when the first arg is an array.