Difference operator?

Legacy User

I have a table with N rows of data. Is there any operator that would convert it into a table of N-1 rows, where each row is a difference of two consecutive rows of the original table?

That is, input:

X  Y
a  b
c  d
e  f

Desired output:

X      Y
c-a  d-b
e-c  f-d

If there is no such operator, can you treat this as a feature request?

Thank you!

steffen

Hello Victor

As far as I know, there is no such operator. Nevertheless, here is a workaround (thanks to RapidMiner for its litte operators which can be combined in powerful ways), tested with the iris-dataset which is also part of RM.

<operator name="Root" class="Process" expanded="yes">
    <operator name="load_data" class="ExampleSource">
        <parameter key="attributes"	value="iris.aml"/>
    </operator>
    <operator name="remove_label" class="FeatureNameFilter">
        <parameter key="filter_special_features"	value="true"/>
        <parameter key="skip_features_with_name"	value="label"/>
    </operator>
    <operator name="copy_data" class="IOMultiplier">
        <parameter key="io_object"	value="ExampleSet"/>
    </operator>
    <operator name="process_minuend" class="OperatorChain" expanded="no">
        <operator name="remove_first_row" class="ExampleFilter">
            <parameter key="condition_class"	value="attribute_value_filter"/>
            <parameter key="invert_filter"	value="true"/>
            <parameter key="parameter_string"	value="id=id_1"/>
        </operator>
        <operator name="remove_ID" class="FeatureNameFilter">
            <parameter key="filter_special_features"	value="true"/>
            <parameter key="skip_features_with_name"	value="id"/>
        </operator>
        <operator name="addID" class="IdTagging">
        </operator>
    </operator>
    <operator name="select_second_set" class="IOSelector">
        <parameter key="io_object"	value="ExampleSet"/>
        <parameter key="select_which"	value="2"/>
    </operator>
    <operator name="process_subtrahend" class="OperatorChain" expanded="yes">
        <operator name="remove_last_row" class="ExampleFilter">
            <parameter key="condition_class"	value="attribute_value_filter"/>
            <parameter key="invert_filter"	value="true"/>
            <parameter key="parameter_string"	value="id=id_150"/>
        </operator>
        <operator name="remove_ID (2)" class="FeatureNameFilter">
            <parameter key="filter_special_features"	value="true"/>
            <parameter key="skip_features_with_name"	value="id"/>
        </operator>
        <operator name="addID (2)" class="IdTagging">
        </operator>
    </operator>
    <operator name="ExampleSetJoin" class="ExampleSetJoin">
        <parameter key="remove_double_attributes"	value="false"/>
    </operator>
    <operator name="FeatureGeneration" class="FeatureGeneration">
        <list key="functions">
          <parameter key="new_a1"	value="-(a1,a1_from_ES2)"/>
          <parameter key="new_a2"	value="-(a2,a2_from_ES2)"/>
        </list>
    </operator>
</operator>

Unfortunately you got to define your functions manually (in "FeatureGeneration"), hence this is only suitable for a smaller amount of attributes.

Note: To make this work in your situation, you must change the dataset-specific parameters (primarily the names of the attributes).
I hope this setup is self-explanatory, if not, feel free to ask.

hope this was helpful

Steffen