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WordPieceTokenizer.Encode

Tokens and ids for one string.

public TokenizationResult Encode(string text)

Parameters — text is the string to encode.

Returns — TokenizationResult, tokens and ids of the same length.

Example — a word outside the vocabulary becomes one unknown token.

using Lodestar.Embeddings.Tokenization;

var vocab = new Dictionary<string, int>(StringComparer.Ordinal)
{
    ["[UNK]"] = 0, ["token"] = 1, ["##ize"] = 2, ["text"] = 3,
};
var tokenizer = new WordPieceTokenizer(
    vocab, unkToken: "[UNK]", continuationPrefix: "##", maxCharsPerWord: 100, lowercase: true);

TokenizationResult known = tokenizer.Encode("tokenize");
TokenizationResult unknown = tokenizer.Encode("zzz");

int pieces = known.Tokens.Count;  // => 2
string missing = unknown.Tokens[0];  // => [UNK]

Remarks — zzz produces a single [UNK], not three. That is WordPiece's rule and it matters when reading a tokenization: a burst of unknown tokens means several unmatched words, never one long one.

Lowercasing, when enabled, happens before matching, so the vocabulary only needs lowercase entries.

Applies to — net10.0, netstandard2.0.

See also — WordPieceTokenizer.EncodeToIds, TokenizationResult.