| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.pig.builtin; |
| |
| import java.io.IOException; |
| import java.math.BigDecimal; |
| import java.math.MathContext; |
| import java.util.Iterator; |
| |
| import org.apache.pig.Accumulator; |
| import org.apache.pig.Algebraic; |
| import org.apache.pig.EvalFunc; |
| import org.apache.pig.PigException; |
| import org.apache.pig.backend.executionengine.ExecException; |
| import org.apache.pig.data.DataBag; |
| import org.apache.pig.data.DataType; |
| import org.apache.pig.data.Tuple; |
| import org.apache.pig.data.TupleFactory; |
| import org.apache.pig.impl.logicalLayer.schema.Schema; |
| |
| |
| /** |
| * This method should never be used directly, use {@link AVG}. |
| */ |
| public class BigDecimalAvg extends EvalFunc<BigDecimal> implements Algebraic, Accumulator<BigDecimal> { |
| |
| private static TupleFactory mTupleFactory = TupleFactory.getInstance(); |
| |
| @Override |
| public BigDecimal exec(Tuple input) throws IOException { |
| try { |
| BigDecimal sum = sum(input); |
| if (sum == null) { |
| // either we were handed an empty bag or a bag |
| // filled with nulls - return null in this case |
| return null; |
| } |
| BigDecimal count = count(input); |
| |
| BigDecimal avg = null; |
| if (count.compareTo(BigDecimal.ZERO) > 0) |
| avg = div(sum, count); |
| return avg; |
| } catch (ExecException ee) { |
| throw ee; |
| } |
| } |
| |
| @Override |
| public String getInitial() { |
| return Initial.class.getName(); |
| } |
| |
| @Override |
| public String getIntermed() { |
| return Intermediate.class.getName(); |
| } |
| |
| @Override |
| public String getFinal() { |
| return Final.class.getName(); |
| } |
| |
| static public class Initial extends EvalFunc<Tuple> { |
| @Override |
| public Tuple exec(Tuple input) throws IOException { |
| try { |
| Tuple t = mTupleFactory.newTuple(2); |
| // input is a bag with one tuple containing |
| // the column we are trying to avg on |
| DataBag bg = (DataBag) input.get(0); |
| BigDecimal d = null; |
| if (bg.iterator().hasNext()) { |
| Tuple tp = bg.iterator().next(); |
| d = (BigDecimal)(tp.get(0)); |
| } |
| t.set(0, d); |
| if (d != null) { |
| t.set(1, BigDecimal.ONE); |
| } else { |
| t.set(1, BigDecimal.ZERO); |
| } |
| return t; |
| } catch (ExecException ee) { |
| throw ee; |
| } catch (Exception e) { |
| int errCode = 2106; |
| String msg = "Error while computing average in " + this.getClass().getSimpleName(); |
| throw new ExecException(msg, errCode, PigException.BUG, e); |
| } |
| } |
| } |
| |
| static public class Intermediate extends EvalFunc<Tuple> { |
| @Override |
| public Tuple exec(Tuple input) throws IOException { |
| try { |
| DataBag b = (DataBag)input.get(0); |
| return combine(b); |
| } catch (ExecException ee) { |
| throw ee; |
| } catch (Exception e) { |
| int errCode = 2106; |
| String msg = "Error while computing average in " + this.getClass().getSimpleName(); |
| throw new ExecException(msg, errCode, PigException.BUG, e); |
| } |
| } |
| } |
| |
| static public class Final extends EvalFunc<BigDecimal> { |
| @Override |
| public BigDecimal exec(Tuple input) throws IOException { |
| try { |
| DataBag b = (DataBag)input.get(0); |
| Tuple combined = combine(b); |
| |
| BigDecimal sum = (BigDecimal)combined.get(0); |
| if (sum == null) { |
| return null; |
| } |
| BigDecimal count = (BigDecimal)combined.get(1); |
| |
| BigDecimal avg = null; |
| if (count.compareTo(BigDecimal.ZERO) > 0) { |
| avg = div(sum,count); |
| } |
| return avg; |
| } catch (ExecException ee) { |
| throw ee; |
| } catch (Exception e) { |
| int errCode = 2106; |
| String msg = "Error while computing average in " + this.getClass().getSimpleName(); |
| throw new ExecException(msg, errCode, PigException.BUG, e); |
| } |
| } |
| } |
| |
| static protected Tuple combine(DataBag values) throws ExecException { |
| BigDecimal sum = BigDecimal.ZERO; |
| BigDecimal count = BigDecimal.ZERO; |
| |
| // combine is called from Intermediate and Final |
| // In either case, Initial would have been called |
| // before and would have sent in valid tuples |
| // Hence we don't need to check if incoming bag |
| // is empty |
| |
| Tuple output = mTupleFactory.newTuple(2); |
| boolean sawNonNull = false; |
| for (Iterator<Tuple> it = values.iterator(); it.hasNext();) { |
| Tuple t = it.next(); |
| BigDecimal d = (BigDecimal)t.get(0); |
| // we count nulls in avg as contributing 0 |
| // a departure from SQL for performance of |
| // COUNT() which implemented by just inspecting |
| // size of the bag |
| if (d == null) { |
| d = BigDecimal.ZERO; |
| } else { |
| sawNonNull = true; |
| } |
| sum = sum.add(d); |
| count = count.add((BigDecimal)t.get(1)); |
| } |
| if (sawNonNull) { |
| output.set(0, sum); |
| } else { |
| output.set(0, null); |
| } |
| output.set(1, count); |
| return output; |
| } |
| |
| static protected BigDecimal count(Tuple input) throws ExecException { |
| DataBag values = (DataBag)input.get(0); |
| Iterator<Tuple> it = values.iterator(); |
| BigDecimal cnt = BigDecimal.ZERO; |
| while (it.hasNext()){ |
| Tuple t = (Tuple)it.next(); |
| if (t != null && t.size() > 0 && t.get(0) != null) |
| cnt = cnt.add(BigDecimal.ONE); |
| } |
| return cnt; |
| } |
| |
| static protected BigDecimal sum(Tuple input) throws ExecException, IOException { |
| DataBag values = (DataBag)input.get(0); |
| |
| // if we were handed an empty bag, return NULL |
| if(values == null || values.size() == 0) { |
| return null; |
| } |
| |
| BigDecimal sum = BigDecimal.ZERO; |
| boolean sawNonNull = false; |
| for (Iterator<Tuple> it = values.iterator(); it.hasNext();) { |
| Tuple t = it.next(); |
| try{ |
| BigDecimal d = (BigDecimal)(t.get(0)); |
| if (d == null) continue; |
| sawNonNull = true; |
| sum = sum.add(d); |
| }catch(RuntimeException exp) { |
| int errCode = 2103; |
| String msg = "Problem while computing sum of BigDecimals."; |
| throw new ExecException(msg, errCode, PigException.BUG, exp); |
| } |
| } |
| |
| if(sawNonNull) { |
| return sum; |
| } else { |
| return null; |
| } |
| } |
| |
| static protected BigDecimal div(BigDecimal dividend, BigDecimal divisor){ |
| // Averages will have IEEE 754R Decimal64 format, 16 digits, and a |
| // rounding mode of HALF_EVEN, the IEEE 754R default |
| return dividend.divide(divisor, MathContext.DECIMAL128); |
| } |
| |
| @Override |
| public Schema outputSchema(Schema input) { |
| return new Schema(new Schema.FieldSchema(null, DataType.BIGDECIMAL)); |
| } |
| |
| /* Accumulator interface */ |
| |
| private BigDecimal intermediateSum = null; |
| private BigDecimal intermediateCount = null; |
| |
| @Override |
| public void accumulate(Tuple b) throws IOException { |
| try { |
| BigDecimal sum = sum(b); |
| if(sum == null) { |
| return; |
| } |
| // set default values |
| if (intermediateSum == null || intermediateCount == null) { |
| intermediateSum = BigDecimal.ZERO; |
| intermediateCount = BigDecimal.ZERO; |
| } |
| |
| BigDecimal count = (BigDecimal)count(b); |
| |
| if (count.compareTo(BigDecimal.ZERO) > 0) { |
| intermediateCount = intermediateCount.add(count); |
| intermediateSum = intermediateSum.add(sum); |
| } |
| } catch (ExecException ee) { |
| throw ee; |
| } catch (Exception e) { |
| int errCode = 2106; |
| String msg = "Error while computing average in " + this.getClass().getSimpleName(); |
| throw new ExecException(msg, errCode, PigException.BUG, e); |
| } |
| } |
| |
| @Override |
| public void cleanup() { |
| intermediateSum = null; |
| intermediateCount = null; |
| } |
| |
| @Override |
| public BigDecimal getValue() { |
| BigDecimal avg = null; |
| if (intermediateCount != null && (intermediateCount.compareTo(BigDecimal.ZERO) > 0)) { |
| avg = div(intermediateSum,intermediateCount); |
| } |
| return avg; |
| } |
| } |