order of executing operators

dan_agape

Hi,

Could someone comment on the following simple process built for test (not practical) purposes?
It retrieves a dataset, learns a decision tree, stores and retrieves the model via
Remember and Recall operators, and applies it for scoring the dataset.

In particular, if one displays the order of executing the process operators,
it shows an attempt to retrieve the model (via Recall) before this is stored (via Remember). A corresponding error is displayed  when trying to run the process.

Since the two operators refer to the same object (identified by the value 'dt' for name), one would expect Remember to be executed first, and then Recall.

Any comments on this surprising execution order are welcome. Moreover, how is the execution order determined, in general, in a RM process?

Thanks,
Dan

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<process version="5.0">
  <context>
    <input/>
    <output/>
    <macros/>
  </context>
  <operator activated="true" class="process" compatibility="5.0.0" expanded="true" name="Root">
    <parameter key="logverbosity" value="3"/>
    <parameter key="random_seed" value="2001"/>
    <parameter key="send_mail" value="1"/>
    <parameter key="process_duration_for_mail" value="30"/>
    <parameter key="encoding" value="SYSTEM"/>
    <parameter key="parallelize_main_process" value="false"/>
    <process expanded="true" height="566" width="900">
      <operator activated="true" class="retrieve" compatibility="5.0.0" expanded="true" height="60" name="Retrieve" width="90" x="45" y="30">
        <parameter key="repository_entry" value="//Samples/data/Golf"/>
      </operator>
      <operator activated="true" class="decision_tree" compatibility="5.0.10" expanded="true" height="76" name="Decision Tree" width="90" x="179" y="30">
        <parameter key="criterion" value="gain_ratio"/>
        <parameter key="minimal_size_for_split" value="4"/>
        <parameter key="minimal_leaf_size" value="2"/>
        <parameter key="minimal_gain" value="0.05"/>
        <parameter key="maximal_depth" value="20"/>
        <parameter key="confidence" value="0.25"/>
        <parameter key="number_of_prepruning_alternatives" value="3"/>
        <parameter key="no_pre_pruning" value="false"/>
        <parameter key="no_pruning" value="false"/>
      </operator>
      <operator activated="true" class="recall" compatibility="5.0.10" expanded="true" height="60" name="Recall" width="90" x="179" y="165">
        <parameter key="name" value="dt"/>
        <parameter key="io_object" value="Model"/>
        <parameter key="remove_from_store" value="true"/>
      </operator>
      <operator activated="true" class="remember" compatibility="5.0.10" expanded="true" height="60" name="Remember" width="90" x="313" y="30">
        <parameter key="name" value="dt"/>
        <parameter key="io_object" value="Model"/>
        <parameter key="store_which" value="1"/>
        <parameter key="remove_from_process" value="true"/>
      </operator>
      <operator activated="true" class="apply_model" compatibility="5.0.10" expanded="true" height="76" name="Apply Model" width="90" x="391" y="170">
        <list key="application_parameters"/>
        <parameter key="create_view" value="false"/>
      </operator>
      <connect from_op="Retrieve" from_port="output" to_op="Decision Tree" to_port="training set"/>
      <connect from_op="Decision Tree" from_port="model" to_op="Remember" to_port="store"/>
      <connect from_op="Decision Tree" from_port="exampleSet" to_op="Apply Model" to_port="unlabelled data"/>
      <connect from_op="Recall" from_port="result" to_op="Apply Model" to_port="model"/>
      <connect from_op="Apply Model" from_port="labelled data" to_port="result 1"/>
      <connect from_op="Apply Model" from_port="model" to_port="result 2"/>
      <portSpacing port="source_input 1" spacing="0"/>
      <portSpacing port="sink_result 1" spacing="0"/>
      <portSpacing port="sink_result 2" spacing="0"/>
      <portSpacing port="sink_result 3" spacing="0"/>
    </process>
  </operator>
</process>

haddock

If I run this XML it gives an error, so I press the double headed blue arrow to see how the flow order is interpreted. I then right click on the "Remember" operator, and take the option to bring the operator forward. Then the process runs fine, try it for yourselves as it shows one of the more advanced RM trace abilities.

IngoRM

Hi Dan,

basically, the execution order is still based on the tree known from previews version. Although it is still possible to view and edit the execution order there, the recommended way is to use the overlay mode in the process view as Haddock has pointed out. Please find more information about this in the RM 5 manual on pages 40 and following.

During process design, you can actually see the operator which is executed before the newly inserted one: the operator before gets a highlighting shadow during the process of dragging the operator into the view. In general, if several possibilities are in principle possible, operators are performed from the upper left to the lower right side.

About the fact that Remember and Recall do not know that they depend on each other: you are right - but this is on purpose. Since the name of the object can also be defined for example via a macro and macros are only set during runtime (and can even be altered there) there is no easy check for this. In such cases the analyst has to ensure that the execution order is correct. The fact that this is possible at all is - from my point of view - one of the strongest points of RapidMiner compared to other solutions.

Cheers,
Ingo

dan_agape

Thanks