CODEWITHSUNDEEP
javaarrayshashmap
nd07
nd07

Reputation: 127

Distance matrix implement

I have two list object like that : A={o1,o2,o3,...on}, B={p1,p2,p3,...pm} (m, n are defined).

I want to store distance among objects from A to B such as : d(o1,p1), d(o1,p2)..., d(o1,pm), d(o2,p1), ...., d(on,pm).

I use a matrix with n rows x m columns to store these distance with rows ordered from o1 to on and columns ordered from p1 to pm

But a problem is that I want to implement a function like that:

public double GetDistance (object obj1, object obj2)

For example, if I call GetDistance(o1, p4) then it will return the value like tis: DistanceMatrix[0][3] = 0.6.

So how can we implement in this case in order to from two objects o1, p4 we can refer that the corresponding row and column in the matrix is 0, 3 (in case I have to use matrix to store distances).

Upvotes: 0

Views: 2056

Answers (1)

Maljam
Maljam

Reputation: 6284

You can use HashMap<object, Integer> pMap and oMap, where the keys are the objects, and the value the index of the column or row: 

Object[] A = //{o1, o2, o3, o4, ... on};
Object[] B = //{p1, p2, p3, p4, ... pm};
HashMap<Object, Integer> oMap = new HashMap<Object, Integer>();
HashMap<Object, Integer> pMap = new HashMap<Object, Integer>();

for(int i = 0 ; i < A.length ; i++) {
    Object o = A[i];
    oMap.add(o, i);
}

for(int i = 0 ; i < B.length ; i++) {
    Object p = B[i];
    pMap.add(p, i);
}

And now you can build you distance matrix, and access the values with: 

public double GetDistance (object obj1, object obj2) {
    //double[][] d = distanceMatrix;
    return d[oMap.get(objt1)][pMap.get(objt2)];
}

Upvotes: 1

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