Unzip.cs

public static class XEnumerable 
{
	public static (T1[], T2[]) Unzip<T1, T2>(this IEnumerable<(T1 x, T2 y)> source) 
	{
		if (source is IReadOnlyCollection<(T1, T2)> roc) 
		{
			T1[] xs = new T1[roc.Count];	
			T2[] ys = new T2[roc.Count];
			int i = 0;
			foreach (var (x, y) in source)
			{
				xs[i] = x;
				ys[i] = y;
				i++;
			}
			return (xs, ys);
		}
		var xsList = new List<T1>();
		var ysList = new List<T2>();
		foreach (var (x, y) in source)
		{
			xsList.Add(x);
			ysList.Add(y);
		}
		return (xsList.ToArray(), ysList.ToArray());
	}
}