MLR model training fails in some cases

[vedrin]

Hi,

While performing some manual testing I've noticed that from time to time (only once in a while) the MLR model training fails with a message like the one below:

ambit:/# time curl -iv -X POST -d 'dataset_uri=http://ambit.uni-plovdiv.bg:8080/ambit2/dataset/6&target=http://ambit.uni-plovdiv.bg:8080/ambit2/feature/11954' http://opentox.ntua.gr:3000/algorithm/mlr

• About to connect() to opentox.ntua.gr port 3000 (#0)
• Trying 147.102.82.32... connected
• Connected to opentox.ntua.gr (147.102.82.32) port 3000 (#0)

  POST /algorithm/mlr HTTP/1.1
  User-Agent: curl/7.18.2 (x86_64-pc-linux-gnu) libcurl/7.18.2 OpenSSL/0.9.8g zlib/1.2.3.3 libidn/1.8 libssh2/0.18
  Host: opentox.ntua.gr:3000
  Accept: /
  Content-Length: 122
  Content-Type: application/x-www-form-urlencoded

  < HTTP/1.1 500 The server encountered an unexpected condition which prevented it from fulfilling the request
  HTTP/1.1 500 The server encountered an unexpected condition which prevented it from fulfilling the request
  < Content-Type: text/plain
  Content-Type: text/plain
  < Date: Thu, 31 Dec 2009 11:55:43 GMT
  Date: Thu, 31 Dec 2009 11:55:43 GMT
  < Accept-Ranges: bytes
  Accept-Ranges: bytes
  < Server: Noelios-Restlet/2.0m3
  Server: Noelios-Restlet/2.0m3
  < Connection: close
  Connection: close
  < Transfer-Encoding: chunked
  Transfer-Encoding: chunked

<
Error Report.
TimeStamp: Thu Dec 31 06:55:43 EST 2009

Error #1
Exception Details: java.lang.IllegalArgumentException: Can't delete class attribute
Explanation: Severe Error while trying to build an MLR model.
For debugging reasons we provide a brief list of the exceptions:

• weka.core.Instances.deleteAttributeAt(Unknown Source)
• org.opentox.algorithm.dataprocessing.DataCleanUp.removeStringAtts(DataCleanUp.java:42)
• org.opentox.algorithm.trainer.MlrTrainer.train(MlrTrainer.java:82)
• org.opentox.resource.Algorithm.post(Algorithm.java:143)
• org.restlet.resource.ServerResource.doHandle(ServerResource.java:340)
• Closing connection #0

real 0m2.206s
user 0m0.004s
sys 0m0.004s