Obtain a remainder

UDFs used to obtain remainders

Integer UDFPMod(INTEGER a, INTEGER b)
Long UDFPMod(Long a, Long b)
Double UDFPMod(Double a, Double b)           

• Description: used to return the remainder by dividing a by b.
• Parameters:
  • a: the dividend, which can be of the INTEGER, LONG, or DOUBLE type
  • b: the divisor, which can be of the INTEGER, LONG, or DOUBLE type

UDF example

• Function registration
  After UDFPMod.java passes the test, register it as a function.

  Note To publish a UDF to a server for production use, the UDF needs to go through packaging, uploading, and registration. You can use the one-click publish function to complete these steps. MaxCompute Studio allows you to run the mvn clean package command, upload a JAR package, and register the UDF in sequence. For more information, see Package, upload, and register a Java program.
• Examples
  After the UDF is registered, execute one of the following statements:

  • Example 1

    select pmodTest(-9L,-4L);

    The result is as follows:

    +-----+
    | _c0 |
    +-----+
    | -1  |
    +-----+

  • Example 2

    select pmodTest(9.0,-4.0);

    The result is as follows:

    +-----+
    | _c0 |
    +-----+
    | -3.0 |
    +-----+

  • Example 3

    select pmodTest(9,4);

    The result is as follows:

    +-----+
    | _c0 |
    +-----+
    | 1   |
    +-----+

UDF code example

package com.aliyun.odps.examples.udf// The package name, which can be defined as needed.
import com.aliyun.odps.udf.UDF;
public class UDFPMod extends UDF {
    // Use data of the LONG type.
    public String evaluate(Long  a,  Long  b)  {
        if  ((a  == null) || (b == null) || b==0L)  {
            return  null;
        }
        Long d=((a % b) + b) % b;
        return d.toString();
    }
    // Use data of the DOUBLE type.
    public String evaluate(Double a, Double b)  {
        if  ((a == null) || (b == null) || b==0.0)  {
            return  null;
        }
        Double d=((a % b) + b) % b;
        return d.toString() ;
    }
    // Use data of the INTEGER type.
    public String evaluate(Integer a, Integer b)  {
        if  ((a == null) || (b == null) || b==0)  {
            return  null;
        }
        Integer d=((a % b) + b) % b;
        return d.toString();
    }
}

UDF unit testing

package com.aliyun.odps.examples.udf// The package name, which can be defined as needed.
import org.junit.Test;
import static org.junit.Assert.assertEquals;
public class TestUDFPMod {
    private UDFPMod udf = new UDFPMod();
    @Test
    public void test_null(){
        assertEquals(null, udf.evaluate(null, 1L));
        assertEquals(null, udf.evaluate(1L, null));
        assertEquals(null, udf.evaluate((Long)null, null));

        assertEquals(null, udf.evaluate(null, 1.0));
        assertEquals(null, udf.evaluate(1.0, null));
        assertEquals(null, udf.evaluate((Double)null, null));
    }
    @Test
    public void test_Normal cases(){
        assertEquals(1L, udf.evaluate(9L, 4L));
        assertEquals(3L, udf.evaluate(-9L, 4L));
        assertEquals(-1L, udf.evaluate(-9L, -4L));
        assertEquals(-3L, udf.evaluate(9L, -4L));
        // An error is returned if the code is not added. null is returned if the code is added.
        assertEquals(null, udf.evaluate(9L, 0L));

        assertEquals(1.0, udf.evaluate(9.0, 4.0));
        assertEquals(3.0, udf.evaluate(-9.0, 4.0));
        assertEquals(-1.0, udf.evaluate(-9.0, -4.0));
        assertEquals(-3.0, udf.evaluate(9.0, -4.0));
        // Nan is returned if the code is not added. null is returned if the code is added.
        assertEquals(null, udf.evaluate(9.0, 0.0));
    }
}