data structure for tabular data

Question

I need to represent data (retreived from a db) representing tabular data (with an x and y axis):

The pair (x,y) has data (an object) associated with it. What would be the most semantically correct way to represent this structure? Of course I have to retrieve the data by indexing either by x or by y, but a symmetric way to represent this would be great.

The difficulty is that x and y alone do not map to the data object, by the pair (x,y) does. I have come up with things like a map from x to another map with y as the key and the data object as the value..but this is not easily invertible and is not very symmetric.

Thanks

Answer 1

Have you considered something like this?

class MyPoint {
    int x;
    int y;
    Object data;
    // setters/getters go below
}

You can use sql (or hibernate/jpa) to retrieve data by x or y coordinate.
Personally, I don't think that 'indexing' should be a part of data structure: database will handle it perfectly without your help.

Answer 2

Your tabular data, i guess, should be in the form of some function, for which f(x) = y, if that's the case I think a HashMap would be ok.

As your question about symmetry, I think you could implement some class

public class Pair{
   private long id;
   private int x;
   private int y;
   private Data data;
}

An then you could store it in some other structure you consider appropriate. As of your indexing, I don't know if that would be a good Idea, given that you can have duplicate values of a given x,y pair for different data sets.