Analyzer · Sentiment Analysis for PHP

use Risan\Sentiment\Analyzer;

final class Analyzer scores text for one language. It is immutable: every with*() method returns a new instance and leaves the original unchanged. An analyzer keeps no state between calls, so one instance can be shared and reused freely.

$analyzer = new Analyzer();                      // English
$analyzer = new Analyzer(Language::Indonesian);  // or new Analyzer('id')

$analyzer = $analyzer
    ->withWords(['cuan' => 2.5, 'bapuk' => -2.0])
    ->withoutWords(['kill'])
    ->withThreshold(0.1);

$result = $analyzer->analyze('Investasinya cuan!');

Constructor

public function __construct(
    Language|string $language = Language::English,
    float $threshold = 0.05,
)

Parameters

Name	Type	Description
`$language`	`Language\|string`	A `Language` case or its code (`'en'`, `'id'`). Defaults to English.
`$threshold`	`float`	The label threshold, from `0` up to but not including `1`. Defaults to `0.05`. See Thresholds.

Throws

Exception	When
`ValueError`	`$language` is a string that is not a known code.
`InvalidArgumentException`	`$threshold` is below `0` or is `1` or higher.

$english = new Analyzer();
$indonesian = new Analyzer(Language::Indonesian);
$strict = new Analyzer('en', threshold: 0.3);

Methods

analyze()

public function analyze(string $text): Result

Scores a text and returns a Result.

Name	Type	Description
`$text`	`string`	The text to analyze. Any length, including empty.

Empty or whitespace-only text returns all zeros and a neutral label. Invalid UTF-8 never throws: invalid bytes are dropped and the rest is scored.

$result = (new Analyzer())->analyze('The food was not good.');

$result->label;    // Label::Negative
$result->compound; // a negative float

withWords()

public function withWords(array $words): static

Returns a new analyzer with words added to the lexicon or their valences overridden.

Name	Type	Description
`$words`	`array<array-key, float\|int>`	Map of `word => valence`. Valences run from `-4` to `4`.

Keys are lower-cased. A numeric key such as '1337' works, even though PHP turns it into an int.

Throws InvalidArgumentException when:

a valence is below -4, above 4 or not a number;
a key is empty;
a key contains whitespace, because a word is a single token and such a key could never match.

$analyzer = (new Analyzer(Language::Indonesian))
    ->withWords(['cuan' => 2.5, 'bapuk' => -2.0]);

$analyzer->withWords(['great' => 9]); // throws InvalidArgumentException

See Customizing the lexicon.

withoutWords()

public function withoutWords(array $words): static

Returns a new analyzer with the given words removed from the lexicon. They then count as neutral words.

Name	Type	Description
`$words`	`list<string>`	Words to remove.

$analyzer = (new Analyzer())->withoutWords(['kill']);

withThreshold()

public function withThreshold(float $threshold): static

Returns a new analyzer with a different label threshold. The scores do not change, only the label.

Name	Type	Description
`$threshold`	`float`	From `0` up to but not including `1`.

Throws InvalidArgumentException when the threshold is outside that range.

$analyzer = (new Analyzer())->withThreshold(0.1); // neutral band is (-0.1, 0.1)

language()

public function language(): Language

Returns the Language of this analyzer, always as an enum case, even when you passed a string code.

(new Analyzer('id'))->language(); // Language::Indonesian

Immutability

$base = new Analyzer();
$tuned = $base->withThreshold(0.3);

$base === $tuned; // false: $base is untouched and keeps threshold 0.05