I think I've developed a simple example which shows that MultipleLabelIterator is somehow not overwriting values defined in previous iterations with new data. Please correct me if I've got this wrong:
What this example is trying to do is:
1) Create a simple example set with two labels (label1, label2)
2) Use MultipleLabelIterator to do the following on each label
3) Run Linear Regression
4) Apply model
5) Compute a new attribute based on value of the predictions of the model.
The problem is that, in step 5, the attribute "prediction(label_1)" changes name with each iteration. So what we ideally want to do is specify "prediction(label_%{a}). However, that doesn't work inside a FeatureGenerator computation, so the workaround suggested in another thread was to rename it to a static name. So the example changes it to "pred_val" and then has a two-step FeatureGenerator to generate a final value called pred_val_sq. Since I want to retain this for each run, I then rename it to "pred_val_sq_%{a}".
This works on the first iteration. However, on the 2nd iteration, the values of "pred_val_sq" still retain the values from the previous iteration, even though that attribute was renamed.
I realize this explanation is somewhat convoluted. Hopefully it will be clearer once the operator chain is run, and you see that "pred_val_sq_1" and "pred_val_sq_2" have identical values.
<operator name="Root" class="Process" expanded="yes">
<operator name="ExampleSetGenerator" class="ExampleSetGenerator">
<parameter key="target_function" value="polynomial"/>
</operator>
<operator name="Change name: label to label1" class="ChangeAttributeRole">
<parameter key="name" value="label"/>
<parameter key="target_role" value="label1"/>
</operator>
<operator name="Change role of label1 to label_1" class="ChangeAttributeName">
<parameter key="new_name" value="label_1"/>
<parameter key="old_name" value="label"/>
</operator>
<operator name="Create attrib: label2" class="FeatureGeneration">
<list key="functions">
<parameter key="label_2" value="+(att1,+(att2,+(att3,+(att4,att5))))"/>
</list>
<parameter key="keep_all" value="true"/>
</operator>
<operator name="Change role of label2 to label_2" class="ChangeAttributeRole">
<parameter key="name" value="label_2"/>
<parameter key="target_role" value="label2"/>
</operator>
<operator name="MultipleLabelIterator" class="MultipleLabelIterator" expanded="yes">
<operator name="LinearRegression" class="LinearRegression">
<parameter key="keep_example_set" value="true"/>
</operator>
<operator name="ModelApplier" class="ModelApplier">
<list key="application_parameters">
</list>
</operator>
<operator name="Remove iteration# from prediction name" class="ChangeAttributeName">
<parameter key="new_name" value="pred_val"/>
<parameter key="old_name" value="prediction(label_%{a})"/>
</operator>
<operator name="Create value derived from pred_val" class="FeatureGeneration" breakpoints="before,after">
<list key="functions">
<parameter key="pred_val_step1" value="+(pred_val,const[1]())"/>
<parameter key="pred_val_sq" value="*(pred_val_step1,pred_val_step1)"/>
</list>
<parameter key="keep_all" value="true"/>
</operator>
<operator name="Change name to add iteration# back to pred_val" class="ChangeAttributeName">
<parameter key="new_name" value="pred_val_%{a}"/>
<parameter key="old_name" value="pred_val"/>
</operator>
<operator name="Rename derived value to add iteration#" class="ChangeAttributeName">
<parameter key="new_name" value="pred_val_sq_%{a}"/>
<parameter key="old_name" value="pred_val_sq"/>
</operator>
</operator>
</operator>
Thanks for any assistance.
Keith
