1. mahout seqdirectory
$ mahout seqdirectory
--input (-i) input Path to job input directory(原始文本文件).
--output (-o) output The directory pathname for output.（<Text,Text>Sequence File）
-ow
功能： 将原始文本数据集转换为< Text, Text > SequenceFile
2. mahout seq2sparke
功能： Convert and preprocesses the dataset（<Text,Text> SequenceFile） into a < Text, VectorWritable > SequenceFile containing term frequencies for each document.
即根据Sequence File转换为tfidf向量文件
说明：If we wanted to use different parsing methods or transformations on the term frequency vectors we could supply different options here e.g.: -ng 2 for bigrams or -n 2 for L2 length normalization
mahout seq2sparse
--output (-o) output The directory pathname for output.
--input (-i) input Path to job input directory.
--weight (-wt) weight The kind of weight to use. Currently TF
or TFIDF. Default: TFIDF
--norm (-n) norm The norm to use, expressed as either a
float or "INF" if you want to use the
Infinite norm. Must be greater or equal
to 0. The default is not to normalize
--overwrite (-ow) If set, overwrite the output directory
--sequentialAccessVector (-seq) (Optional) Whether output vectors should
be SequentialAccessVectors. If set true
else false
--namedVector (-nv) (Optional) Whether output vectors should
be NamedVectors. If set true else false
-i Sequence File文件目录
-o 向量文件输出目录
-wt 权重类型，支持TF或者TFIDF两种选项，默认TFIDF
-n 使用的正规化，使用浮点数或者"INF"表示，
-ow 指定该参数，将覆盖已有的输出目录
-seq 指定该参数，那么输出的向量是SequentialAccessVectors
-nv 指定该参数，那么输出的向量是NamedVectors
3. mahout split
功能：Split the preprocessed dataset into training and testing sets.
将预处理的tfidf向量集转换为training和testing向量集
$ 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
说明：如上是将向量数据集分为训练数据和检测数据，以随机40-60拆分
3. mahout trainnb
功能：训练分类器
mahout trainnb
--input (-i) input Path to job input directory.
--output (-o) output The directory pathname for output.
--alphaI (-a) alphaI Smoothing parameter. Default is 1.0
--trainComplementary (-c) Train complementary? Default is false.
--labelIndex (-li) labelIndex The path to store the label index in
--overwrite (-ow) If present, overwrite the output directory
before running job
--help (-h) Print out help
--tempDir tempDir Intermediate output directory
--startPhase startPhase First phase to run
--endPhase endPhase Last phase to run
-i 输入路径
-o 输出路径
-a
-c 补偿性训练
-li label index文件的目录
-ow 指定该参数，删除输出目录
tempDir MapReduce作业的中间结果
startPhase 运行的第一个阶段
endPhase 运行的最后一个阶段
4. mahout testnb
功能：检验Bayes分类器
mahout testnb
--input (-i) input Path to job input directory.
--output (-o) output The directory pathname for output.
--overwrite (-ow) If present, overwrite the output directory
before running job
--model (-m) model The path to the model built during training
--testComplementary (-c) Test complementary? Default is false.
--runSequential (-seq) Run sequential?
--labelIndex (-l) labelIndex The path to the location of the label index
--help (-h) Print out help
--tempDir tempDir Intermediate output directory
--startPhase startPhase First phase to run
--endPhase endPhase Last phase to run
-i 输入路径
-o 输出路径
-ow 覆盖输出目录
-c