DoubleArrays.java

package com.github.lwhite1.tablesaw.util;

import com.github.lwhite1.tablesaw.api.NumericColumn;
import com.github.lwhite1.tablesaw.table.TemporaryView;
import com.github.lwhite1.tablesaw.table.ViewGroup;
import com.google.common.base.Preconditions;

/**
 * Utility functions for creating 2D double arrays from columns and other arrays
 */
public class DoubleArrays {

    public static double[] toN(int n) {
        double[] result = new double[n];
        for (int i = 0; i < n; i++) {
            result[i] = i;
        }
        return result;
    }

    public static double[][] to2dArray(NumericColumn... columns) {
        Preconditions.checkArgument(columns.length >= 1);
        int obs = columns[0].size();
        double[][] allVals = new double[obs][columns.length];

        for (int r = 0; r < obs; r++) {
            for (int c = 0; c < columns.length; c++) {
                allVals[r][c] = columns[c].getFloat(r);
                allVals[r][c] = columns[c].getFloat(r);
            }
        }
        return allVals;
    }

    public static double[][] to2dArray(ViewGroup views, int columnNumber) {

        int viewCount = views.size();

        double[][] allVals = new double[viewCount][];
        for (int viewNumber = 0; viewNumber < viewCount; viewNumber++) {
            TemporaryView view = views.get(viewNumber);
            allVals[viewNumber] = new double[view.rowCount()];
            NumericColumn numericColumn = view.numericColumn(columnNumber);
            for (int r = 0; r < view.rowCount(); r++) {
                allVals[viewNumber][r] = numericColumn.getFloat(r);
            }
        }
        return allVals;
    }

    public static double[][] to2dArray(double[] x, double[] y) {
        double[][] allVals = new double[x.length][2];
        for (int i = 0; i < x.length; i++) {
            allVals[i][0] = x[i];
            allVals[i][1] = y[i];
        }
        return allVals;
    }

    public static double[][] to2dArray(NumericColumn x, NumericColumn y) {
        double[][] allVals = new double[x.size()][2];
        for (int i = 0; i < x.size(); i++) {
            allVals[i][0] = x.getFloat(i);
            allVals[i][1] = y.getFloat(i);
        }
        return allVals;
    }
}