| /* |
| * 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 datafu.pig.stats; |
| |
| import java.io.IOException; |
| import java.util.ArrayList; |
| import java.util.Iterator; |
| import java.util.List; |
| |
| import org.apache.pig.Accumulator; |
| import org.apache.pig.Algebraic; |
| import org.apache.pig.EvalFunc; |
| import org.apache.pig.FuncSpec; |
| import org.apache.pig.PigException; |
| import org.apache.pig.data.DataBag; |
| import org.apache.pig.data.DataByteArray; |
| import org.apache.pig.data.DataType; |
| import org.apache.pig.data.Tuple; |
| import org.apache.pig.data.TupleFactory; |
| import org.apache.pig.impl.logicalLayer.FrontendException; |
| import org.apache.pig.impl.logicalLayer.schema.Schema; |
| import org.apache.pig.backend.executionengine.ExecException; |
| |
| |
| /** |
| * Use {@link VAR} |
| */ |
| public class DoubleVAR extends EvalFunc<Double> implements Algebraic, Accumulator<Double> { |
| private static TupleFactory mTupleFactory = TupleFactory.getInstance(); |
| |
| @Override |
| public Double exec(Tuple input) throws IOException { |
| try { |
| Double sum = sum(input); |
| Double sumSquare = sumSquare(input); |
| |
| if(sum == null) { |
| // either we were handed an empty bag or a bag |
| // filled with nulls - return null in this case |
| return null; |
| } |
| long count = count(input); |
| |
| Double var = null; |
| if (count > 0){ |
| Double avg = new Double(sum / count); |
| Double avgSquare = new Double(sumSquare / count); |
| var = avgSquare - avg*avg; |
| } |
| |
| return var; |
| } catch (ExecException ee) { |
| throw ee; |
| } |
| } |
| |
| public String getInitial() { |
| return Initial.class.getName(); |
| } |
| |
| public String getIntermed() { |
| return Intermediate.class.getName(); |
| } |
| |
| public String getFinal() { |
| return Final.class.getName(); |
| } |
| |
| static public class Initial extends EvalFunc<Tuple> { |
| @Override |
| public Tuple exec(Tuple input) throws IOException { |
| Tuple t = mTupleFactory.newTuple(3); |
| try { |
| // input is a bag with one tuple containing |
| // the column we are trying to get variance |
| DataBag bg = (DataBag) input.get(0); |
| Double d = null; |
| Iterator<Tuple> iter = bg.iterator(); |
| if(iter.hasNext()) { |
| Tuple tp = iter.next(); |
| d = (Double)tp.get(0); |
| } |
| |
| if (iter.hasNext()) |
| { |
| throw new RuntimeException("Expected only one tuple in bag"); |
| } |
| |
| if (d == null){ |
| t.set(0, null); |
| t.set(1, null); |
| t.set(2, 0L); |
| } |
| else { |
| t.set(0, d); |
| t.set(1, d*d); |
| t.set(2, 1L); |
| } |
| return t; |
| } catch(NumberFormatException nfe) { |
| nfe.printStackTrace(); |
| // invalid input, |
| // treat this input as null |
| try { |
| t.set(0, null); |
| t.set(1, null); |
| t.set(2, 0L); |
| } catch (ExecException e) { |
| throw e; |
| } |
| return t; |
| } catch (ExecException ee) { |
| ee.printStackTrace(); |
| throw ee; |
| } catch (Exception e) { |
| e.printStackTrace(); |
| int errCode = 2106; |
| String msg = "Error while computing variance 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 variacne in " + this.getClass().getSimpleName(); |
| throw new ExecException(msg, errCode, PigException.BUG, e); |
| |
| } |
| } |
| } |
| |
| static public class Final extends EvalFunc<Double> { |
| @Override |
| public Double exec(Tuple input) throws IOException { |
| try { |
| DataBag b = (DataBag)input.get(0); |
| Tuple combined = combine(b); |
| |
| Double sum = (Double)combined.get(0); |
| Double sumSquare = (Double)combined.get(1); |
| if(sum == null) { |
| return null; |
| } |
| Long count = (Long)combined.get(2); |
| |
| Double var = null; |
| |
| if (count > 0) { |
| Double avg = new Double(sum / count); |
| Double avgSquare = new Double(sumSquare / count); |
| var = avgSquare - avg*avg; |
| } |
| return var; |
| } catch (ExecException ee) { |
| throw ee; |
| } catch (Exception e) { |
| int errCode = 2106; |
| String msg = "Error while computing variance in " + this.getClass().getSimpleName(); |
| throw new ExecException(msg, errCode, PigException.BUG, e); |
| } |
| } |
| } |
| |
| static protected Tuple combine(DataBag values) throws ExecException{ |
| double sum = 0; |
| double sumSquare = 0; |
| long totalCount = 0; |
| |
| // 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(3); |
| boolean sawNonNull = false; |
| for (Iterator<Tuple> it = values.iterator(); it.hasNext();) { |
| Tuple t = it.next(); |
| Double d = (Double)t.get(0); |
| Double dSquare = (Double)t.get(1); |
| Long count = (Long)t.get(2); |
| |
| // we count nulls in var as contributing 0 |
| // a departure from SQL for performance of |
| // COUNT() which implemented by just inspecting |
| // size of the bag |
| if(d == null) { |
| d = 0.0; |
| dSquare = 0.0; |
| } else { |
| sawNonNull = true; |
| } |
| sum += d; |
| sumSquare += dSquare; |
| totalCount += count; |
| } |
| if(sawNonNull) { |
| output.set(0, new Double(sum)); |
| output.set(1, new Double(sumSquare)); |
| } else { |
| output.set(0, null); |
| output.set(1, null); |
| } |
| output.set(2, Long.valueOf(totalCount)); |
| return output; |
| } |
| |
| static protected long count(Tuple input) throws ExecException { |
| DataBag values = (DataBag)input.get(0); |
| long cnt = 0; |
| Iterator<Tuple> it = values.iterator(); |
| while (it.hasNext()){ |
| Tuple t = (Tuple)it.next(); |
| if (t != null && t.size() > 0 && t.get(0) != null) |
| cnt ++; |
| } |
| |
| return cnt; |
| } |
| |
| static protected Double sum(Tuple input) throws ExecException, IOException { |
| DataBag values = (DataBag)input.get(0); |
| |
| // if we were handed an empty bag, return NULL |
| if(values.size() == 0) { |
| return null; |
| } |
| |
| double sum = 0; |
| boolean sawNonNull = false; |
| for (Iterator<Tuple> it = values.iterator(); it.hasNext();) { |
| Tuple t = it.next(); |
| try{ |
| Double d= (Double)t.get(0); |
| if (d == null) continue; |
| sawNonNull = true; |
| sum += d; |
| }catch(RuntimeException exp) { |
| int errCode = 2103; |
| String msg = "Problem while computing sum of values."; |
| throw new ExecException(msg, errCode, PigException.BUG, exp); |
| } |
| } |
| |
| if(sawNonNull) { |
| return new Double(sum); |
| } else { |
| return null; |
| } |
| } |
| |
| static protected Double sumSquare(Tuple input) throws ExecException, IOException { |
| DataBag values = (DataBag)input.get(0); |
| |
| // if we were handed an empty bag, return NULL |
| if(values.size() == 0) { |
| return null; |
| } |
| |
| double sumSquare = 0; |
| boolean sawNonNull = false; |
| for (Iterator<Tuple> it = values.iterator(); it.hasNext();) { |
| Tuple t = it.next(); |
| try{ |
| Double d = (Double)t.get(0); |
| if (d == null) continue; |
| sawNonNull = true; |
| sumSquare += d*d; |
| }catch(RuntimeException exp) { |
| int errCode = 2103; |
| String msg = "Problem while computing sum of squared values."; |
| throw new ExecException(msg, errCode, PigException.BUG, exp); |
| } |
| } |
| |
| if(sawNonNull) { |
| return new Double(sumSquare); |
| } else { |
| return null; |
| } |
| } |
| |
| @Override |
| public Schema outputSchema(Schema input) { |
| return new Schema(new Schema.FieldSchema(null, DataType.DOUBLE)); |
| } |
| |
| /* Accumulator interface implementation */ |
| private Double intermediateSumSquare = null; |
| private Double intermediateSum = null; |
| private Long intermediateCount = null; |
| |
| @Override |
| public void accumulate(Tuple b) throws IOException { |
| try { |
| Double sum = sum(b); |
| if(sum == null) { |
| return; |
| } |
| |
| Double sumSquare = sumSquare(b); |
| if(sumSquare == null) { |
| return; |
| } |
| |
| // set default values |
| if (intermediateSum == null || intermediateCount == null) { |
| intermediateSumSquare = 0.0; |
| intermediateSum = 0.0; |
| intermediateCount = (long) 0; |
| } |
| |
| long count = (Long)count(b); |
| |
| if (count > 0) { |
| intermediateCount += count; |
| intermediateSum += sum; |
| intermediateSumSquare += sumSquare; |
| } |
| } catch (ExecException ee) { |
| throw ee; |
| } catch (Exception e) { |
| int errCode = 2106; |
| String msg = "Error while computing variance in " + this.getClass().getSimpleName(); |
| throw new ExecException(msg, errCode, PigException.BUG, e); |
| } |
| } |
| |
| @Override |
| public void cleanup() { |
| intermediateSumSquare = null; |
| intermediateSum = null; |
| intermediateCount = null; |
| } |
| |
| @Override |
| public Double getValue() { |
| Double var = null; |
| if (intermediateCount != null && intermediateCount > 0) { |
| Double avg = new Double(intermediateSum / intermediateCount); |
| Double avgSquare = new Double(intermediateSumSquare / intermediateCount); |
| var = avgSquare - avg*avg; |
| } |
| return var; |
| } |
| } |