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Calculation by Groups

Hi,

This is a newbie's question...I have a data which looks like the below:

Group Value
1 78
1 64
1 75
2 66
2 54
2 72
2 77
3 57
3 59
3 61

Now, i want to do a calculation by groups. And this calculation is ABS("Value" - Group Average). The output datafile should look like the below:

Group Value Result
1 78 5.666666667
1 64 8.333333333
1 75 2.666666667
2 66 1.25
2 54 13.25
2 72 4.75
2 77 9.75
3 57 2
3 59 0
3 61 2

This is exactly group processing. How do we do this in Rapid Miner?

Many thanks for your help,
Shubha

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Shubha

Shubha wrote:

Hi,

This is a newbie's question...I have a data which looks like the below:

Group Value
1 78
1 64
1 75
2 66
2 54
2 72
2 77
3 57
3 59
3 61

Now, i want to do a calculation by groups. And this calculation is ABS("Value" - Group Average). The output datafile should look like the below:

Group Value Result
1 78 5.666666667
1 64 8.333333333
1 75 2.666666667
2 66 1.25
2 54 13.25
2 72 4.75
2 77 9.75
3 57 2
3 59 0
3 61 2

This is exactly group processing. How do we do this in Rapid Miner?

Many thanks for your help,
Shubha

Does the "Attribute Constructor" or the "ValueSubgroupIterator" help me with this respect?

Shubha

Does this take too many steps to do in Rapidminer?

BR, Shubha

IngoRM

Hi,

it's actually pretty simple:


<operator name="Root" class="Process" expanded="yes">
    <operator name="Generate Data" class="OperatorChain" expanded="no">
        <operator name="ExampleSetGenerator" class="ExampleSetGenerator">
            <parameter key="target_function"	value="sum"/>
            <parameter key="number_examples"	value="12"/>
            <parameter key="number_of_attributes"	value="2"/>
        </operator>
        <operator name="AttributeFilter" class="AttributeFilter">
            <parameter key="condition_class"	value="attribute_name_filter"/>
            <parameter key="parameter_string"	value="label"/>
            <parameter key="invert_filter"	value="true"/>
            <parameter key="apply_on_special"	value="true"/>
        </operator>
        <operator name="AttributeSubsetPreprocessing" class="AttributeSubsetPreprocessing" expanded="yes">
            <parameter key="condition_class"	value="attribute_name_filter"/>
            <parameter key="attribute_name_regex"	value="att1"/>
            <operator name="FrequencyDiscretization" class="FrequencyDiscretization">
                <parameter key="number_of_bins"	value="3"/>
                <parameter key="range_name_type"	value="short"/>
            </operator>
        </operator>
        <operator name="Sorting" class="Sorting">
            <parameter key="attribute_name"	value="att1"/>
        </operator>
    </operator>
    <operator name="ValueIterator" class="ValueIterator" expanded="yes">
        <parameter key="attribute"	value="att1"/>
        <operator name="ExampleFilter" class="ExampleFilter">
            <parameter key="condition_class"	value="attribute_value_filter"/>
            <parameter key="parameter_string"	value="att1 = %{loop_value}"/>
        </operator>
        <operator name="Aggregation" class="Aggregation">
            <list key="aggregation_attributes">
              <parameter key="att2"	value="average"/>
            </list>
        </operator>
        <operator name="DataMacroDefinition" class="DataMacroDefinition">
            <parameter key="macro"	value="current_average"/>
            <parameter key="macro_type"	value="data_value"/>
            <parameter key="attribute_name"	value="average(att2)"/>
            <parameter key="example_index"	value="1"/>
        </operator>
        <operator name="IOConsumer" class="IOConsumer">
            <parameter key="io_object"	value="ExampleSet"/>
            <parameter key="deletion_type"	value="delete_one"/>
        </operator>
        <operator name="AttributeConstruction" class="AttributeConstruction">
            <list key="function_descriptions">
              <parameter key="att2_abs_avg"	value="abs(att2 - %{current_average})"/>
            </list>
        </operator>
    </operator>
    <operator name="ExampleSetMerge" class="ExampleSetMerge">
    </operator>
</operator>

Please note that the first chain is only used for generating data like you have described. The ValueIterator together with the aggregation and the merge do the trick.

All the best,
Ingo

Shubha

Thank you very much Ingo...

A question is:
Can I do this without splitting the data into 3 data parts( according to the groups)...

IngoRM

Hi,

with a different (and more complex) setup for RM 4.4 (coming this week): yes, it would also be possible without "dividing" the data. But what's wrong with it? Actually, the different data parts are only views on the same data set and therefore should be no problem at all.

Cheers,
Ingo

Shubha

Oh, is it? They are the views and not exactly 3 different data being generated? And so, it would not consume the memory space for my large data?

Thanks,
Shubha

Shubha

Hi,

One last question,

While I join daasets in the end by "ExampleSetMerge", the group order is changed. How to get back the original group order while merging? Is there a way to reverse the order number of the 3 different datasets generated?

Thanks,
Shubha

IngoRM

Well, a little bit of digging around yourself would probably not hurt: in the process I sent to you, there already was a Sorting operator at the end of the data generation process. Use another one directly after the merge.

Cheers,
Ingo

Shubha

Thanks Ingo... Sorting is fine... But actually my problem is,

We have the generated split datasets. While joining itself, can we join in the order? Or atleast in the descending order? This would help another problem of mine...

Thanks, Shubha