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