/// <summary>
/// Partitions the operator state of a <see cref="DataStream{TElement}"/> by the given key positions.
/// </summary>
/// <param name="fields">The position of the fields on which the <see cref="DataStream{TElement}"/> will be grouped.</param>
/// <returns>The <see cref="DataStream{TElement}"/> with partitioned state (i.e. <see cref="KeyedStream{T,TKey}"/>)</returns>
public KeyedStream <TElement, int> KeyBy(params int[] fields)
{
if (Type is BasicArrayTypeInfo <TElement> ||
Type is PrimitiveArrayTypeInfo <TElement> )
{
return(KeyBy(KeySelectorUtil.GetSelectorForArray <TElement, int>(fields, Type)));
}
return(KeyBy <int>(new Keys <TElement> .ExpressionKeys <TElement>(fields, Type)));
}
private KeyedStream <TElement, TKey> KeyBy <TKey>(Keys <TElement> keys) => new KeyedStream <TElement, TKey>(this, Clean(KeySelectorUtil.GetSelectorForKeys <TElement, TKey>(keys,
Type, ExecutionConfig)));
