Hi, all,
I have a case where each element in the Dataset is an Arraylist. And I may
add some elements in the Arraylist. Therefore, I use map operator to add
elements. However, due to dataset is immutable. Every time I use a mapper
to add an element, it actually creates another arraylist and add element in
it.
Below is the code as an example.
DataSet<ArrayList<Integer>> dataset0 = env.fromElements(new ArrayList<>(),
new ArrayList<>());
DataSet<ArrayList<Integer>> dataset1 = dataset0.map(
new MapFunction<ArrayList<Integer>, ArrayList<Integer>>() {
@Override
public ArrayList<Integer> map(ArrayList<Integer> value) throws Exception {
value.add(10);
return value;
}
});
DataSet<ArrayList<Integer>> unioned = dataset0.union(dataset1);
unioned.print();
The output is “[] [] [10] [10]”
But I expect “[10] [10] [10] [10]”
Any advice is appreciated.
--
Best Regards.
---
Xing FENG
The University of New South Wales
PhD Student
Mobile: +61 413 8572 88
