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"Using Select with Loop Operator"

jeganathanvelujeganathanvelu Member Posts: 17 Contributor I
edited June 2019 in Help

I have used loop operator and the result set is ioo object collections [ one for each month in the data]. I want to select the last output data set and process further.
In the select operator i have to specify an index number to represent which object in the collection i have to pick.

can i some how identify how many objects are created by the loop operator and provide that as input to the Select operator index ??

Thanks Jegan


  • homburghomburg Moderator, Employee, Member Posts: 114  RM Data Scientist
    Hi Jegan,

    you may use a macro for your loop operator. In the parameters tab you can enable "set iteration macro" and define a name for it. By default the macro value is incresed by one with every loop iteration. For the index in the select operator you specify %{macroname} and receive the highest index. Of course you may also specify the same value for the number of iterations in the loop and for the index. This can also be a macro, just have a look at "Set Macro" operator.

  • bkrieverbkriever RapidMiner Certified Analyst, Member Posts: 11 Contributor II
    Here is an example process similar to what Helge described that may help if you are not familiar with the macros in loops and extracting macros:
    In this case I aggregated on the label value to get the distinct number of values.  In your case you could replace this with month.

    <?xml version="1.0" encoding="UTF-8" standalone="no"?>
    <process version="6.0.008">
      <operator activated="true" class="process" compatibility="6.0.008" expanded="true" name="Process">
        <process expanded="true">
          <operator activated="true" class="generate_data" compatibility="6.0.008" expanded="true" height="60" name="Generate Data" width="90" x="45" y="30">
            <parameter key="target_function" value="multi classification"/>
            <parameter key="number_of_attributes" value="2"/>
            <parameter key="attributes_lower_bound" value="0.0"/>
          <operator activated="true" class="aggregate" compatibility="6.0.008" expanded="true" height="76" name="Aggregate" width="90" x="179" y="30">
            <list key="aggregation_attributes"/>
            <parameter key="group_by_attributes" value="label"/>
          <operator activated="true" class="extract_macro" compatibility="6.0.008" expanded="true" height="60" name="Extract Macro" width="90" x="313" y="30">
            <parameter key="macro" value="NumExamples"/>
            <list key="additional_macros"/>
          <operator activated="true" class="loop" compatibility="6.0.008" expanded="true" height="76" name="Loop" width="90" x="179" y="120">
            <parameter key="set_iteration_macro" value="true"/>
            <parameter key="iterations" value="%{NumExamples}"/>
            <process expanded="true">
              <operator activated="true" class="generate_attributes" compatibility="6.0.008" expanded="true" height="76" name="Generate Attributes" width="90" x="246" y="30">
                <list key="function_descriptions">
                  <parameter key="DummyAttribute_%{iteration}" value="%{iteration}"/>
              <connect from_port="input 1" to_op="Generate Attributes" to_port="example set input"/>
              <connect from_op="Generate Attributes" from_port="example set output" to_port="output 1"/>
              <portSpacing port="source_input 1" spacing="0"/>
              <portSpacing port="source_input 2" spacing="0"/>
              <portSpacing port="sink_output 1" spacing="0"/>
              <portSpacing port="sink_output 2" spacing="0"/>
          <operator activated="true" class="select" compatibility="6.0.008" expanded="true" height="60" name="Select" width="90" x="313" y="120">
            <parameter key="index" value="%{NumExamples}"/>
          <connect from_op="Generate Data" from_port="output" to_op="Aggregate" to_port="example set input"/>
          <connect from_op="Aggregate" from_port="example set output" to_op="Extract Macro" to_port="example set"/>
          <connect from_op="Aggregate" from_port="original" to_op="Loop" to_port="input 1"/>
          <connect from_op="Loop" from_port="output 1" to_op="Select" to_port="collection"/>
          <connect from_op="Select" from_port="selected" to_port="result 1"/>
          <portSpacing port="source_input 1" spacing="0"/>
          <portSpacing port="sink_result 1" spacing="0"/>
          <portSpacing port="sink_result 2" spacing="0"/>

  • jeganathanvelujeganathanvelu Member Posts: 17 Contributor I
    Thanks for your help: the above solution solved my issue :)
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