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Write a fitted vectorizer out without blocking the caller.

public Task SaveAsync(Stream destination, CancellationToken cancellationToken = default)

Parameters — destination is a writable stream, left open. cancellationToken cancels the write.

Returns — Task, completing when the vectorizer has been written.

Exceptions — InvalidOperationException when nothing has been fitted yet. ArgumentNullException for a null stream. OperationCanceledException when cancelled.

Example — the same round trip as Save, asynchronously.

using Lodestar.Text.Vectorization;

static async Task<int> RoundTripAsync()
{
    var cv = new CountVectorizer();
    cv.Fit(["the cat eats", "the dog eats"]);

    using var buffer = new MemoryStream();
    await cv.SaveAsync(buffer);
    buffer.Position = 0;

    CountVectorizer restored = await CountVectorizer.LoadAsync(buffer);
    return restored.Transform(["the cat"]).ColumnCount;
}

int columns = RoundTripAsync().GetAwaiter().GetResult();  // => 4

The GetAwaiter().GetResult() is only what lets a synchronous example drive an async one; in async code the call is simply await.

Remarks — there is no SaveAsync(string path) overload to match Save's: opening the file is the caller's, and a FileStream created with useAsync: true is what makes the asynchrony reach the disk rather than stopping at a buffer.

Worth using when the destination is a network stream or a large file, and not otherwise — a vocabulary is small, and the synchronous overload avoids the machinery.

Applies to — net10.0, netstandard2.0.

See also — CountVectorizer.Save, CountVectorizer.LoadAsync.