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Programming-Idioms

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Idiom #351 Create a zipped collection

Generate a "zipped" list z of pairs of elements from the lists a, b having the same length n.

The result z will contain n pairs.

z = zip(a, b)
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import static java.util.stream.Stream.of;
List f(Iterable ... c) {
    List<Iterator> a
        = of(c).map(Iterable::iterator)
               .toList();
    List<List> list = new ArrayList<>();
    List t;
    Iterator x;
    int i, n = a.size();
    boolean b;
    do {
        b = false;
        t = new ArrayList<>();
        for (i = 0; i != n; ++i)
            if ((x = a.get(i)).hasNext())
                b = t.add(x.next());
            else t.add(null);
        if (b) list.add(t);
    } while (b);
    return list;
}
z = a.zip(b)
let z = a.into_iter().zip(b).collect::<Vec<_>>();
New implementation...
< > ⌨
reilas 
z = zip(a, b)
List f(Iterable ... c) {
    List<Iterator> a
        = of(c).map(Iterable::iterator)
               .toList();
    List<List> list = new ArrayList<>();
    List t;
    Iterator x;
    int i, n = a.size();
    boolean b;
    do {
        b = false;
        t = new ArrayList<>();
        for (i = 0; i != n; ++i)
            if ((x = a.get(i)).hasNext())
                b = t.add(x.next());
            else t.add(null);
        if (b) list.add(t);
    } while (b);
    return list;
}
z = a.zip(b)
let z = a.into_iter().zip(b).collect::<Vec<_>>();