HMM模型实例 mahout官网上的案例

原理：http://www.cnblogs.com/CheeseZH/p/4229910.html

Example

To build a Hidden Markov Model and use it to build some predictions, try a simple example like this:

Create an input file to train the model. Here we have a sequence drawn from the set of states 0, 1, 2, and 3, separated by space characters.

$ echo "0 1 2 2 2 1 1 0 0 3 3 3 2 1 2 1 1 1 1 2 2 2 0 0 0 0 0 0 2 2 2 0 0 0 0 0 0 2 2 2 3 3 3 3 3 3 2 3 2 3 2 3 2 1 3 0 0 0 1 0 1 0 2 1 2 1 2 1 2 3 3 3 3 2 2 3 2 1 1 0" > hmm-input

Now run the baumwelch job to train your model, after first setting MAHOUT_LOCAL to true, to use your local file system.

$ export MAHOUT_LOCAL=true
$ $MAHOUT_HOME/bin/mahout baumwelch -i hmm-input -o hmm-model -nh 3 -no 4 -e .0001 -m 1000

Output like the following should appear in the console.

Initial probabilities: 
0 1 2 
1.0 0.0 3.5659361683006626E-251 
Transition matrix:
  0 1 2 
0 6.098919959130616E-5 0.9997275322964165 2.1147850399214744E-4 
1 7.404648706054873E-37 0.9086408633885092 0.09135913661149081 
2 0.2284374545687356 7.01786289571088E-11 0.7715625453610858 
Emission matrix: 
  0 1 2 3 
0 0.9999997858591223 2.0536163836449762E-39 2.1414087769942127E-7 1.052441093535389E-27 
1 7.495656581383351E-34 0.2241269055449904 0.4510889999455847 0.32478409450942497 
2 0.815051477991782 0.18494852200821799 8.465660634827592E-33 2.8603899591778015E-36 
14/03/22 09:52:21 INFO driver.MahoutDriver: Program took 180 ms (Minutes: 0.003)

The model trained with the input set now is in the file 'hmm-model', which we can use to build a predicted sequence.

$ $MAHOUT_HOME/bin/mahout hmmpredict -m hmm-model -o hmm-predictions -l 10

To see the predictions:

$ cat hmm-predictions 
0 1 3 3 2 2 2 2 1 2