| /* |
| * Copyright 2016, Yahoo! Inc. |
| * Licensed under the terms of the Apache License 2.0. See LICENSE file at the project root for terms. |
| */ |
| |
| package com.yahoo.sketches.pig.quantiles; |
| |
| import java.io.IOException; |
| import java.util.Comparator; |
| |
| import org.apache.pig.EvalFunc; |
| import org.apache.pig.data.DataByteArray; |
| import org.apache.pig.data.Tuple; |
| |
| import com.yahoo.memory.Memory; |
| import com.yahoo.sketches.ArrayOfStringsSerDe; |
| import com.yahoo.sketches.quantiles.ItemsSketch; |
| |
| /** |
| * This UDF is to get the parameter K from a given sketch. |
| * This can be useful for debugging a work flow to make sure that resulting sketches |
| * have the intended K, and, therefore, the accuracy |
| */ |
| public class GetKFromStringsSketch extends EvalFunc<Integer> { |
| |
| @Override |
| public Integer exec(final Tuple input) throws IOException { |
| if (input.size() != 1) { |
| throw new IllegalArgumentException("expected one input"); |
| } |
| |
| if (!(input.get(0) instanceof DataByteArray)) { |
| throw new IllegalArgumentException("expected a DataByteArray as a sketch, got " |
| + input.get(0).getClass().getSimpleName()); |
| } |
| final DataByteArray dba = (DataByteArray) input.get(0); |
| final ItemsSketch<String> sketch = |
| ItemsSketch.getInstance(Memory.wrap(dba.get()), Comparator.naturalOrder(), |
| new ArrayOfStringsSerDe()); |
| |
| return sketch.getK(); |
| } |
| |
| } |