使用 HashMap/表或矩阵有什么区别？

Question

I am trying to import a table in which different data type is stored.

As you can see same nº has several rows and I want to have access to each one as the column but I am not sure if the best strategy to manipulate data in Java is using tables.

Which is the difference between using a HashMap/ a table or a Matrix?

Answer 1

I would make a class for n, like this:

public class nDegree{ 
    private ArrayList<Integer> prevAct;  //For example, you would add 2 and 4 to this list if your object was for n = 3 etc.
    private ArrayList<Integer> timeRel;
    private ArrayList<Integer> frequency;

    public nDegree(ArrayList<Integer> prevAct, ArrayList<Integer> timeRel, ArrayList<Integer> frequency) {
        this.prevAct = prevAct;
        this.timeRel = timeRel;
        this.frequency = frequency;
    }

    public ArrayList<Integer> getPrevAct() {
        return prevAct;
    }

    public void setPrevAct(ArrayList<Integer> prevAct) {
        this.prevAct = prevAct;
    }
    public ArrayList<Integer> getTimeRel() {
        return timeRel;
    }
    public void setTimeRel(ArrayList<Integer> timeRel) {
        this.timeRel = timeRel;
    }
    public ArrayList<Integer> getFrequency() {
        return frequency;
    }
    public void setFrequency(ArrayList<Integer> frequency) {
        this.frequency = frequency;
    }

}

Then you could create an object of that for each entry, and save it into a HashMap by it's n value, like this:

HashMap<Integer,NDegree> vals = new HashMap<Integer,NDegree>();

NDegree one = new NDegree(pList,tList,fList);

vals.put(1,one);

etc.. Then to access each element by it's n value you can just do something like this:

ArrayList<Integer> oneFrequency = vals.get(<n value>).getFrequency();

If the N values are always sequential, you could also use a List for holding the objects:

ArrayList<NDegree> vals = new ArrayList<NDegree>();

vals.add(nOne);
...

Then access a particular one like this:

ndList.get(<n-value>);

Or you can iterate over each value for each N entry, and iterate over the map to access all of the N values or whatever you need.