Apache Simple Linear Regression In Java using Math Library

Question

I am quite a newbie in using the apache library for a simple linear regress. Task: I want to calculate the slope.

I have two linear lists, i.e., x-list and y-list. Y list values are the series of number. I am populating x-list by fetching value from a hashmap.

However, when I am trying to apply simpleRegression utility of apache library I am facing below difficulty:

Here is my code:

while(i< segmentI)
                {
                    xList.add(Double.parseDouble(timeStamp.get(i)));
                    yList.add(Double.parseDouble("1"));
                    i++;
                }
                for(int m=0; i< segmentI; i++)
                {
                        simpleRegression.addData(new double[][]{
                                {xList.get(m),yList.get(m)}
                        });

                }

Doubt: Is there any way can I create new double[][] before passing it to simpleRegression. Also, new double[][]-it is a matrix then what would be the value of [0,1], [0,2]... so on because we don't have anything like that in single ArrayList.

Anything in this regard will be helpful.

The Apache foundation supports lots of different projects. Which Apache library are you using? -- Y-list always contains a value of 1 -- Then the output of the linear regression will have slope 0 and intercept 1 — Joni
– Joni, Commented Aug 2, 2020 at 0:35
I mean to say for y, i.e., y2-y1 will always be 1. For the library I am using: commons-math3 — Ria Sachdeva
– Ria Sachdeva, Commented Aug 2, 2020 at 1:30
Create a 2-dimension array from two 1-D arrays: Java turning two arrays into one two-dimensional array. Then you can use the examples provided in the documentation for simple regression. — andrewJames
– andrewJames, Commented Aug 2, 2020 at 2:14

Joni · Accepted Answer · 2020-08-02 02:19:31Z

1

Is there any way can I create new double[][] before passing it to simpleRegression

Yes. For example

            double[][] data = new data[1][2];

            for(int m=0; m < segmentI; m++)
            {
                    data[0][0] = xList.get(m);
                    data[0][1] = yList.get(m);
                    simpleRegression.addData(data);
            }

You know there's also a method that you can call without an array?

simpleRegression.addData(xList.get(m), yList.get(m));

answered Aug 2, 2020 at 2:19

Joni

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Ria Sachdeva · Accepted Answer · 2020-08-02 21:57:26Z

0

This worked with below changes: double[][] pqr={ArrayUtils.toPrimitive(yList.toArray(new Double[0])),ArrayUtils.toPrimitive(xList.toArray(new Double[0]))}; simpleRegression.addData(pqr);

answered Aug 2, 2020 at 21:57

Ria Sachdeva

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