运行Mahout分类算法，分析20newsgroup的分类过程

1.由于虚拟机不能联网，直接运行./example/bin/classify-20newsgroups.sh出现很多问题，索性直接看目标运行classify-20newsgroups.sh

#!/bin/bash
#
# 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.
#

#
# Downloads the 20newsgroups dataset, trains and tests a classifier.
#
# To run:  change into the mahout directory and type:
# examples/bin/classify-20newsgroups.sh

if [ "$1" = "--help" ] || [ "$1" = "--?" ]; then
  echo "This script runs SGD and Bayes classifiers over the classic 20 News Groups."
  exit
fi

SCRIPT_PATH=${0%/*}
if [ "$0" != "$SCRIPT_PATH" ] && [ "$SCRIPT_PATH" != "" ]; then
  cd $SCRIPT_PATH
fi
START_PATH=`pwd`

if [ "$HADOOP_HOME" != "" ] && [ "$MAHOUT_LOCAL" == "" ] ; then
  HADOOP="$HADOOP_HOME/bin/hadoop"
  if [ ! -e $HADOOP ]; then
    echo "Can't find hadoop in $HADOOP, exiting"
    exit 1
  fi
fi

WORK_DIR=/tmp/mahout-work-${USER}
algorithm=( cnaivebayes naivebayes sgd clean)
if [ -n "$1" ]; then
  choice=$1
else
  echo "Please select a number to choose the corresponding task to run"
  echo "1. ${algorithm[0]}"
  echo "2. ${algorithm[1]}"
  echo "3. ${algorithm[2]}"
  echo "4. ${algorithm[3]} -- cleans up the work area in $WORK_DIR"
  read -p "Enter your choice : " choice
fi

echo "ok. You chose $choice and we'll use ${algorithm[$choice-1]}"
alg=${algorithm[$choice-1]}

if [ "x$alg" != "xclean" ]; then
  echo "creating work directory at ${WORK_DIR}"

  mkdir -p ${WORK_DIR}
  if [ ! -e ${WORK_DIR}/20news-bayesinput ]; then
    if [ ! -e ${WORK_DIR}/20news-bydate ]; then
      if [ ! -f ${WORK_DIR}/20news-bydate.tar.gz ]; then
        echo "Downloading 20news-bydate"
        curl http://people.csail.mit.edu/jrennie/20Newsgroups/20news-bydate.tar.gz -o ${WORK_DIR}/20news-bydate.tar.gz
      fi
      mkdir -p ${WORK_DIR}/20news-bydate
      echo "Extracting..."
      cd ${WORK_DIR}/20news-bydate && tar xzf ../20news-bydate.tar.gz && cd .. && cd ..
    fi
  fi
fi
#echo $START_PATH
cd $START_PATH
cd ../..

set -e

if [ "x$alg" == "xnaivebayes"  -o  "x$alg" == "xcnaivebayes" ]; then
  c=""

  if [ "x$alg" == "xcnaivebayes" ]; then
    c=" -c"
  fi

  set -x
  echo "Preparing 20newsgroups data"
  rm -rf ${WORK_DIR}/20news-all
  mkdir ${WORK_DIR}/20news-all
  cp -R ${WORK_DIR}/20news-bydate/*/* ${WORK_DIR}/20news-all

  if [ "$HADOOP_HOME" != "" ] && [ "$MAHOUT_LOCAL" == "" ] ; then
    echo "Copying 20newsgroups data to HDFS"
    set +e
    $HADOOP dfs -rmr ${WORK_DIR}/20news-all
    set -e
    $HADOOP dfs -put ${WORK_DIR}/20news-all ${WORK_DIR}/20news-all
  fi

  echo "Creating sequence files from 20newsgroups data"
  ./bin/mahout seqdirectory \
    -i ${WORK_DIR}/20news-all \
    -o ${WORK_DIR}/20news-seq -ow

  echo "Converting sequence files to vectors"
  ./bin/mahout seq2sparse \
    -i ${WORK_DIR}/20news-seq \
    -o ${WORK_DIR}/20news-vectors  -lnorm -nv  -wt tfidf

  echo "Creating training and holdout set with a random 80-20 split of the generated vector dataset"
  ./bin/mahout split \
    -i ${WORK_DIR}/20news-vectors/tfidf-vectors \
    --trainingOutput ${WORK_DIR}/20news-train-vectors \
    --testOutput ${WORK_DIR}/20news-test-vectors  \
    --randomSelectionPct 40 --overwrite --sequenceFiles -xm sequential

  echo "Training Naive Bayes model"
  ./bin/mahout trainnb \
    -i ${WORK_DIR}/20news-train-vectors -el \
    -o ${WORK_DIR}/model \
    -li ${WORK_DIR}/labelindex \
    -ow $c

  echo "Self testing on training set"

  ./bin/mahout testnb \
    -i ${WORK_DIR}/20news-train-vectors\
    -m ${WORK_DIR}/model \
    -l ${WORK_DIR}/labelindex \
    -ow -o ${WORK_DIR}/20news-testing $c

  echo "Testing on holdout set"

  ./bin/mahout testnb \
    -i ${WORK_DIR}/20news-test-vectors\
    -m ${WORK_DIR}/model \
    -l ${WORK_DIR}/labelindex \
    -ow -o ${WORK_DIR}/20news-testing $c

elif [ "x$alg" == "xsgd" ]; then
  if [ ! -e "/tmp/news-group.model" ]; then
    echo "Training on ${WORK_DIR}/20news-bydate/20news-bydate-train/"
    ./bin/mahout org.apache.mahout.classifier.sgd.TrainNewsGroups ${WORK_DIR}/20news-bydate/20news-bydate-train/
  fi
  echo "Testing on ${WORK_DIR}/20news-bydate/20news-bydate-test/ with model: /tmp/news-group.model"
  ./bin/mahout org.apache.mahout.classifier.sgd.TestNewsGroups --input ${WORK_DIR}/20news-bydate/20news-bydate-test/ --model /tmp/news-group.model
elif [ "x$alg" == "xclean" ]; then
  rm -rf ${WORK_DIR}
  rm -rf /tmp/news-group.model
fi
# Remove the work directory
#

上边是Mahout自带的classify-20newsgroups.sh文件 的内容，下边是改之后的内容。

#!/bin/bash
#
# 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.
#

#
# Downloads the 20newsgroups dataset, trains and tests a classifier.
#
# To run:  change into the mahout directory and type:
# examples/bin/classify-20newsgroups.sh

if [ "$1" = "--help" ] || [ "$1" = "--?" ]; then
  echo "This script runs SGD and Bayes classifiers over the classic 20 News Groups."
  exit
fi

SCRIPT_PATH=${0%/*}
if [ "$0" != "$SCRIPT_PATH" ] && [ "$SCRIPT_PATH" != "" ]; then
  cd $SCRIPT_PATH
fi
START_PATH=`pwd`

if [ "$HADOOP_HOME" != "" ] && [ "$MAHOUT_LOCAL" == "" ] ; then
  HADOOP="$HADOOP_HOME/bin/hadoop"
  if [ ! -e $HADOOP ]; then
    echo "Can't find hadoop in $HADOOP, exiting"
    exit 1
  fi
fi
//工作目录
WORK_DIR=/tmp/mahout-work-${USER}
algorithm=( cnaivebayes naivebayes sgd clean)
if [ -n "$1" ]; then
  choice=$1
else
  echo "Please select a number to choose the corresponding task to run"
  echo "1. ${algorithm[0]}"
  echo "2. ${algorithm[1]}"
  echo "3. ${algorithm[2]}"
  echo "4. ${algorithm[3]} -- cleans up the work area in $WORK_DIR"
  read -p "Enter your choice : " choice
fi

echo "ok. You chose $choice and we'll use ${algorithm[$choice-1]}"
alg=${algorithm[$choice-1]}
//然后从http://people.csail.mit.edu/jrennie/20Newsgroups/20news-bydate.tar.gz直接下载，将下载的文件放到WORK_DIR中然后
if [ "x$alg" != "xclean" ]; then
  echo "creating work directory at ${WORK_DIR}"
  mkdir -p ${WORK_DIR}
  if [ ! -e ${WORK_DIR}/20news-bayesinput ]; then
    if [ ! -e ${WORK_DIR}/20news-bydate ]; then
      if [ ! -f ${WORK_DIR}/20news-bydate.tar.gz ]; then
       echo "Downloading 20news-bydate"
        curl http://people.csail.mit.edu/jrennie/20Newsgroups/20news-bydate.tar.gz -o ${WORK_DIR}/20news-bydate.tar.gz
      fi
      mkdir -p ${WORK_DIR}/20news-bydate
      echo "Extracting..."
      cd ${WORK_DIR}/20news-bydate && tar xzf ../20news-bydate.tar.gz && cd .. && cd ..
    fi
  fi
fi

#echo $START_PATH
cd $START_PATH
cd ../..

set -e

if [ "x$alg" == "xnaivebayes"  -o  "x$alg" == "xcnaivebayes" ]; then
  c=""

  if [ "x$alg" == "xcnaivebayes" ]; then
    c=" -c"
  fi
  set -x
  echo "Preparing 20newsgroups data"
  rm -rf ${WORK_DIR}/20news-all
  mkdir ${WORK_DIR}/20news-all
  cp -R ${WORK_DIR}/20news-bydate/*/* ${WORK_DIR}/20news-all        
//20news-bydate中包括训练集和测试集，合起来是完整的20newsgroups
 //这3句是自己加上的，直接运行会找不到文件问题出现。

  export HADOOP=hadoop  #I add it
  export HWORK_DIR=hdfs://localhost:9000${WORK_DIR} 
  export CLASSPATH=$CLASSPATH:$MAHOUT_HOME/lib
#  if [ "$HADOOP_HOME" != "" ] && [ "$MAHOUT_LOCAL" == "" ] ; then
    echo "Copying 20newsgroups data to HDFS"
#    set +e
#    $HADOOP dfs -rmr ${WORK_DIR}/20news-all
#    set -e
#    $HADOOP dfs -put ${WORK_DIR}/20news-all ${HWORK_DIR}/20news-all
# fi





  echo "Creating sequence files from 20newsgroups data"
  ./bin/mahout seqdirectory \
    -i ${WORK_DIR}/20news-all \
    -o ${WORK_DIR}/20news-seq -ow

  echo "Converting sequence files to vectors"
  ./bin/mahout seq2sparse \
    -i ${WORK_DIR}/20news-seq \
    -o ${WORK_DIR}/20news-vectors  -lnorm -nv  -wt tfidf

  echo "Creating training and holdout set with a random 80-20 split of the generated vector dataset"
  ./bin/mahout split \
    -i ${WORK_DIR}/20news-vectors/tfidf-vectors \
    --trainingOutput ${WORK_DIR}/20news-train-vectors \
    --testOutput ${WORK_DIR}/20news-test-vectors  \
    --randomSelectionPct 40 --overwrite --sequenceFiles -xm sequential

  echo "Training Naive Bayes model"
  ./bin/mahout trainnb \
    -i ${WORK_DIR}/20news-train-vectors -el \
    -o ${WORK_DIR}/model \
    -li ${WORK_DIR}/labelindex \
    -ow $c

  echo "Self testing on training set"

  ./bin/mahout testnb \
    -i ${WORK_DIR}/20news-train-vectors\
    -m ${WORK_DIR}/model \
    -l ${WORK_DIR}/labelindex \
    -ow -o ${WORK_DIR}/20news-testing $c

  echo "Testing on holdout set"

  ./bin/mahout testnb \
    -i ${WORK_DIR}/20news-test-vectors\
    -m ${WORK_DIR}/model \
    -l ${WORK_DIR}/labelindex \
    -ow -o ${WORK_DIR}/20news-testing $c

elif [ "x$alg" == "xsgd" ]; then
  if [ ! -e "/tmp/news-group.model" ]; then
    echo "Training on ${WORK_DIR}/20news-bydate/20news-bydate-train/"
    ./bin/mahout org.apache.mahout.classifier.sgd.TrainNewsGroups ${WORK_DIR}/20news-bydate/20news-bydate-train/
  fi
  echo "Testing on ${WORK_DIR}/20news-bydate/20news-bydate-test/ with model: /tmp/news-group.model"
  ./bin/mahout org.apache.mahout.classifier.sgd.TestNewsGroups --input ${WORK_DIR}/20news-bydate/20news-bydate-test/ --model /tmp/news-group.model
elif [ "x$alg" == "xclean" ]; then
  rm -rf ${WORK_DIR}
  rm -rf /tmp/news-group.model
fi




2.


  echo "Creating sequence files from 20newsgroups data"
  ./bin/mahout seqdirectory \
    -i ${WORK_DIR}/20news-all \
    -o ${WORK_DIR}/20news-seq -ow

从MAHOUT_HOME/conf文件夹下的driver.classes.default.props文件可以找到，此命令实际是运行org.apache.mahout.text.SequenceFilesFromDirectory类，此类是一个Hadoop的Job。只有Mapper，SequenceFilesFromDirectoryMapper，没有Reducer。

3.
echo "Converting sequence files to vectors"
  ./bin/mahout seq2sparse \
    -i ${WORK_DIR}/20news-seq \
    -o ${WORK_DIR}/20news-vectors  -lnorm -nv  -wt tfidf

实际运行org.apache.mahout.vectorizer.SparseVectorsFromSequenceFiles类，包含4个Job DocumentProcessor，DictionaryVectorizer，HighDFWordsPruner和TFIDFConverter



4.
  echo "Creating training and holdout set with a random 80-20 split of the generated vector dataset"
  ./bin/mahout split \
    -i ${WORK_DIR}/20news-vectors/tfidf-vectors \
    --trainingOutput ${WORK_DIR}/20news-train-vectors \
    --testOutput ${WORK_DIR}/20news-test-vectors  \
    --randomSelectionPct 40 --overwrite --sequenceFiles -xm sequential

实际运行org.apache.mahout.utils.SplitInput类，Job类是org.apache.mahout.utils.SplitInputJob。SplitInputMapper，SplitInputReducer。




5.
  echo "Training Naive Bayes model"
  ./bin/mahout trainnb \
    -i ${WORK_DIR}/20news-train-vectors -el \
    -o ${WORK_DIR}/model \
    -li ${WORK_DIR}/labelindex \
    -ow $c

实际运行org.apache.mahout.classifier.naivebayes.training.TrainNaiveBayesJob类，3步，indexInstances，weightSummer和thetaSummer。



6.
 echo "Self testing on training set"

  ./bin/mahout testnb \
    -i ${WORK_DIR}/20news-train-vectors\
    -m ${WORK_DIR}/model \
    -l ${WORK_DIR}/labelindex \
    -ow -o ${WORK_DIR}/20news-testing $c
实际运行org.apache.mahout.classifier.naivebayes.test.TestNaiveBayesDriver类，BayesTestMapper。




7.
  echo "Testing on holdout set"

  ./bin/mahout testnb \
    -i ${WORK_DIR}/20news-test-vectors\
    -m ${WORK_DIR}/model \
    -l ${WORK_DIR}/labelindex \
    -ow -o ${WORK_DIR}/20news-testing $c