| /** |
| * 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.hadoop.mapreduce.lib.fieldsel; |
| |
| import java.util.List; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| import org.apache.hadoop.io.Text; |
| |
| /** |
| * This class implements a mapper/reducer class that can be used to perform |
| * field selections in a manner similar to unix cut. The input data is treated |
| * as fields separated by a user specified separator (the default value is |
| * "\t"). The user can specify a list of fields that form the map output keys, |
| * and a list of fields that form the map output values. If the inputformat is |
| * TextInputFormat, the mapper will ignore the key to the map function. and the |
| * fields are from the value only. Otherwise, the fields are the union of those |
| * from the key and those from the value. |
| * |
| * The field separator is under attribute "mapreduce.fieldsel.data.field.separator" |
| * |
| * The map output field list spec is under attribute |
| * "mapreduce.fieldsel.map.output.key.value.fields.spec". |
| * The value is expected to be like "keyFieldsSpec:valueFieldsSpec" |
| * key/valueFieldsSpec are comma (,) separated field spec: fieldSpec,fieldSpec,fieldSpec ... |
| * Each field spec can be a simple number (e.g. 5) specifying a specific field, or a range |
| * (like 2-5) to specify a range of fields, or an open range (like 3-) specifying all |
| * the fields starting from field 3. The open range field spec applies value fields only. |
| * They have no effect on the key fields. |
| * |
| * Here is an example: "4,3,0,1:6,5,1-3,7-". It specifies to use fields 4,3,0 and 1 for keys, |
| * and use fields 6,5,1,2,3,7 and above for values. |
| * |
| * The reduce output field list spec is under attribute |
| * "mapreduce.fieldsel.reduce.output.key.value.fields.spec". |
| * |
| * The reducer extracts output key/value pairs in a similar manner, except that |
| * the key is never ignored. |
| * |
| */ |
| @InterfaceAudience.Public |
| @InterfaceStability.Stable |
| public class FieldSelectionHelper { |
| |
| public static Text emptyText = new Text(""); |
| public static final String DATA_FIELD_SEPERATOR = |
| "mapreduce.fieldsel.data.field.separator"; |
| public static final String MAP_OUTPUT_KEY_VALUE_SPEC = |
| "mapreduce.fieldsel.map.output.key.value.fields.spec"; |
| public static final String REDUCE_OUTPUT_KEY_VALUE_SPEC = |
| "mapreduce.fieldsel.reduce.output.key.value.fields.spec"; |
| |
| |
| /** |
| * Extract the actual field numbers from the given field specs. |
| * If a field spec is in the form of "n-" (like 3-), then n will be the |
| * return value. Otherwise, -1 will be returned. |
| * @param fieldListSpec an array of field specs |
| * @param fieldList an array of field numbers extracted from the specs. |
| * @return number n if some field spec is in the form of "n-", -1 otherwise. |
| */ |
| private static int extractFields(String[] fieldListSpec, |
| List<Integer> fieldList) { |
| int allFieldsFrom = -1; |
| int i = 0; |
| int j = 0; |
| int pos = -1; |
| String fieldSpec = null; |
| for (i = 0; i < fieldListSpec.length; i++) { |
| fieldSpec = fieldListSpec[i]; |
| if (fieldSpec.length() == 0) { |
| continue; |
| } |
| pos = fieldSpec.indexOf('-'); |
| if (pos < 0) { |
| Integer fn = Integer.valueOf(fieldSpec); |
| fieldList.add(fn); |
| } else { |
| String start = fieldSpec.substring(0, pos); |
| String end = fieldSpec.substring(pos + 1); |
| if (start.length() == 0) { |
| start = "0"; |
| } |
| if (end.length() == 0) { |
| allFieldsFrom = Integer.parseInt(start); |
| continue; |
| } |
| int startPos = Integer.parseInt(start); |
| int endPos = Integer.parseInt(end); |
| for (j = startPos; j <= endPos; j++) { |
| fieldList.add(j); |
| } |
| } |
| } |
| return allFieldsFrom; |
| } |
| |
| private static String selectFields(String[] fields, List<Integer> fieldList, |
| int allFieldsFrom, String separator) { |
| String retv = null; |
| int i = 0; |
| StringBuffer sb = null; |
| if (fieldList != null && fieldList.size() > 0) { |
| if (sb == null) { |
| sb = new StringBuffer(); |
| } |
| for (Integer index : fieldList) { |
| if (index < fields.length) { |
| sb.append(fields[index]); |
| } |
| sb.append(separator); |
| } |
| } |
| if (allFieldsFrom >= 0) { |
| if (sb == null) { |
| sb = new StringBuffer(); |
| } |
| for (i = allFieldsFrom; i < fields.length; i++) { |
| sb.append(fields[i]).append(separator); |
| } |
| } |
| if (sb != null) { |
| retv = sb.toString(); |
| if (retv.length() > 0) { |
| retv = retv.substring(0, retv.length() - 1); |
| } |
| } |
| return retv; |
| } |
| |
| public static int parseOutputKeyValueSpec(String keyValueSpec, |
| List<Integer> keyFieldList, List<Integer> valueFieldList) { |
| String[] keyValSpecs = keyValueSpec.split(":", -1); |
| |
| String[] keySpec = keyValSpecs[0].split(","); |
| |
| String[] valSpec = new String[0]; |
| if (keyValSpecs.length > 1) { |
| valSpec = keyValSpecs[1].split(","); |
| } |
| |
| FieldSelectionHelper.extractFields(keySpec, keyFieldList); |
| return FieldSelectionHelper.extractFields(valSpec, valueFieldList); |
| } |
| |
| public static String specToString(String fieldSeparator, String keyValueSpec, |
| int allValueFieldsFrom, List<Integer> keyFieldList, |
| List<Integer> valueFieldList) { |
| StringBuffer sb = new StringBuffer(); |
| sb.append("fieldSeparator: ").append(fieldSeparator).append("\n"); |
| |
| sb.append("keyValueSpec: ").append(keyValueSpec).append("\n"); |
| sb.append("allValueFieldsFrom: ").append(allValueFieldsFrom); |
| sb.append("\n"); |
| sb.append("keyFieldList.length: ").append(keyFieldList.size()); |
| sb.append("\n"); |
| for (Integer field : keyFieldList) { |
| sb.append("\t").append(field).append("\n"); |
| } |
| sb.append("valueFieldList.length: ").append(valueFieldList.size()); |
| sb.append("\n"); |
| for (Integer field : valueFieldList) { |
| sb.append("\t").append(field).append("\n"); |
| } |
| return sb.toString(); |
| } |
| |
| private Text key = null; |
| private Text value = null; |
| |
| public FieldSelectionHelper() { |
| } |
| |
| public FieldSelectionHelper(Text key, Text val) { |
| this.key = key; |
| this.value = val; |
| } |
| |
| public Text getKey() { |
| return key; |
| } |
| |
| public Text getValue() { |
| return value; |
| } |
| |
| public void extractOutputKeyValue(String key, String val, |
| String fieldSep, List<Integer> keyFieldList, List<Integer> valFieldList, |
| int allValueFieldsFrom, boolean ignoreKey, boolean isMap) { |
| if (!ignoreKey) { |
| val = key + val; |
| } |
| String[] fields = val.split(fieldSep); |
| |
| String newKey = selectFields(fields, keyFieldList, -1, fieldSep); |
| String newVal = selectFields(fields, valFieldList, allValueFieldsFrom, |
| fieldSep); |
| if (isMap && newKey == null) { |
| newKey = newVal; |
| newVal = null; |
| } |
| |
| if (newKey != null) { |
| this.key = new Text(newKey); |
| } |
| if (newVal != null) { |
| this.value = new Text(newVal); |
| } |
| } |
| } |