Cypher中的线性回归函数

Question

如何在密码中找到线性回归R平方系数？

我希望在Oracle Database中定义的Cypher中具有等效的线性回归函数：

REGR_R2(column_y, column_x)

Answer 1

您可以编写自己的Java procedures in Neo4j并从Cypher中调用它们。

对于回归函数，我们可以使用apache commons SimpleRegression class。

以下代码将创建名为regr的过程，它将返回给定X和Y属性的基本回归值。

您可以将此程序从Cypher称为：regr('MY_LABEL', 'Y', 'X')

public class Regression {
@Context public GraphDatabaseService db;

// Result class
public static class Output {
    public double r2;
    public double avg_x;
    public double avg_y;
    public double slope;
    public Output(double r2, double avg_x, double avg_y, double slope){
        this.r2 = r2;
        this.avg_x = avg_x;
        this.avg_y = avg_y;
        this.slope = slope;
    }
}

@Procedure("regr")
public Stream<Output> regr(@Name("label") String label,
                             @Name("property_y") String y, @Name("property_x") String x ) {

    SimpleRegression regr = new SimpleRegression(false);
    double regr_avgx = 0;
    double regr_avgy = 0;
    int count = 0;

    try (ResourceIterator it = db.findNodes(Label.label(label))) {
        while (it.hasNext()) {
            Node node = (Node)it.next();
            if(node.hasProperty(x) && node.hasProperty(y))
            {
                Object prop_x = node.getProperty(x);
                Object prop_y = node.getProperty(y);

                regr_avgx += (double) ((Long)prop_x);
                regr_avgy += (double) ((Long)prop_y);
                regr.addData((double) ((Long)prop_x), (double) ((Long)prop_y));
                count++;
            }
        }
    }
    regr_avgx /= count;
    regr_avgy /= count;
    return Stream.of(new Output(regr.getRSquare(), regr_avgx, regr_avgy, regr.getSlope()));
}
}