Nearest neighbours always gives the same prediction ¿? !!

traveria

Hello, I am having an astonishing result:

I run a very simple test with nearest neighbors (see xml code below) and I am using a training dataset and an test dataset (see short datasets below).

The seldom result is that I always get the same value for the predicted value, despite the test example I use 

If I use the "ExampleSetGenerator" instead of reading a dataset in a file (activate it in the model I include below) I get a different prediction for every new test example I use, as it is expected.

Can anyone explain what is the reason for getting always the same prediction if I read data from a file?? ???

Any hint or solution will be welcomed!!!!

<operator name="Root" class="Process" expanded="yes">
    <operator name="ExampleSource" class="ExampleSource">
        <parameter key="attributes" value="/home/miquel/Documents/I+D+I/MICROPREDICCIO/RapidMiner WORKSPACE/PFC 2008-2009/prova_suma.aml"/>
    </operator>
    <operator name="ExampleSetGenerator" class="ExampleSetGenerator" activated="no">
        <parameter key="number_examples" value="10000"/>
        <parameter key="target_function" value="polynomial"/>
    </operator>
    <operator name="NearestNeighbors" class="NearestNeighbors">
    </operator>
    <operator name="ExampleSource (4)" class="ExampleSource">
        <parameter key="attributes" value="/home/miquel/Documents/I+D+I/MICROPREDICCIO/RapidMiner WORKSPACE/PFC 2008-2009/prova_suma_test.aml"/>
        <parameter key="permutate" value="true"/>
    </operator>
    <operator name="ExampleSetGenerator (2)" class="ExampleSetGenerator" activated="no">
        <parameter key="number_examples" value="10"/>
        <parameter key="target_function" value="polynomial"/>
    </operator>
    <operator name="ExampleRangeFilter" class="ExampleRangeFilter">
        <parameter key="first_example" value="2"/>
        <parameter key="last_example" value="2"/>
    </operator>
    <operator name="ModelApplier" class="ModelApplier">
        <list key="application_parameters">
        </list>
        <parameter key="create_view" value="true"/>
        <parameter key="keep_model" value="true"/>
    </operator>
</operator>

TRAINING DATA

1 1.6 0.84 0 0.76
2 2.17 0.91 0.3 0.96
3 1.61 0.14 0.48 1
4 0.84 -0.76 0.6 1
5 0.74 -0.96 0.7 1
6 1.5 -0.28 0.78 1
7 2.5 0.66 0.85 1
8 2.89 0.99 0.9 1
9 2.37 0.41 0.95 1
10 1.46 -0.54 1 1
11 1.04 -1 1.04 1
12 1.54 -0.54 1.08 1
13 2.53 0.42 1.11 1
14 3.14 0.99 1.15 1
15 2.83 0.65 1.18 1
16 1.92 -0.29 1.2 1
17 1.27 -0.96 1.23 1
18 1.5 -0.75 1.26 1
19 2.43 0.15 1.28 1
20 3.21 0.91 1.3 1

TEST DATA

21 3.16 0.84 1.32 1
22 2.33 -0.01 1.34 1
23 1.52 -0.85 1.36 1
24 1.47 -0.91 1.38 1
25 2.27 -0.13 1.4 1
26 3.18 0.76 1.41 1
27 3.39 0.96 1.43 1
28 2.72 0.27 1.45 1
29 1.8 -0.66 1.46 1
30 1.49 -0.99 1.48 1

haddock

Hi,

I'm not sure the result is as surprising as you think. I can replicate your problem on your own data if I simply include the left hand column as a normal attribute, even though it looks looks much more like an Id attribute. If you treat it like one your "surprising" result disappears  So I think you should check your AML file to see how you've been handling that column.

Here's some code to illustrate the point, if you leave "1'" as the value for "select_which" in the very first operator all the predictions are the same, but they are not all the same if you insert "2" instead. That is because the second example source marks column one as an Id column, whereas the first does not.

<operator name="Root" class="Process" expanded="yes">
    <operator name="OperatorSelector" class="OperatorSelector" expanded="yes">
        <operator name="SimpleExampleSource" class="SimpleExampleSource">
            <parameter key="filename"	value="C:\Users\CJFP\Documents\rm_workspace\prob.txt"/>
            <parameter key="label_column"	value="2"/>
        </operator>
        <operator name="SimpleExampleSource (2)" class="SimpleExampleSource">
            <parameter key="filename"	value="C:\Users\CJFP\Documents\rm_workspace\prob.txt"/>
            <parameter key="label_column"	value="2"/>
            <parameter key="id_column"	value="1"/>
        </operator>
    </operator>
    <operator name="IOMultiplier" class="IOMultiplier">
        <parameter key="io_object"	value="ExampleSet"/>
    </operator>
    <operator name="ExampleRangeFilter" class="ExampleRangeFilter">
        <parameter key="first_example"	value="1"/>
        <parameter key="last_example"	value="20"/>
    </operator>
    <operator name="NearestNeighbors" class="NearestNeighbors">
    </operator>
    <operator name="IOSelector" class="IOSelector">
        <parameter key="io_object"	value="ExampleSet"/>
    </operator>
    <operator name="ExampleRangeFilter (2)" class="ExampleRangeFilter">
        <parameter key="first_example"	value="21"/>
        <parameter key="last_example"	value="30"/>
    </operator>
    <operator name="ModelApplier" class="ModelApplier">
        <parameter key="keep_model"	value="true"/>
        <list key="application_parameters">
        </list>
        <parameter key="create_view"	value="true"/>
    </operator>
</operator>

I've attached the datafile with all 30 examples, you'll need to adjust the path to it in order to run the demo.

[attachment deleted by admin]