1 | .. _Outliers: |
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2 | |
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3 | Outliers |
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4 | ======== |
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5 | |
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6 | .. image:: ../icons/Outliers.png |
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7 | |
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8 | Simple outlier detection by comparing distances between examples. |
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9 | |
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10 | Signals |
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11 | ------- |
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12 | |
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13 | Inputs: |
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14 | - Examples (ExampleTable) |
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15 | Attribute-valued data set. |
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16 | - Distance matrix |
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17 | A matrix of example distances. |
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18 | |
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19 | Outputs: |
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20 | - Outliers (ExampleTable) |
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21 | Attribute-valued data set containing only examples that are outliers. |
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22 | Meta attribute Z-score is added. |
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23 | - Inliers (ExampleTable) |
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24 | Attribute-valued data set containing only examples that are not |
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25 | outliers. Meta attribute Z-score is added. |
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26 | - Examples with Z-scores (ExampleTable) |
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27 | Attribute-valued data set containing examples from input data with |
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28 | corresponding Z-scores as meta attribute. |
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29 | |
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30 | |
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31 | |
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32 | |
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33 | Description |
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34 | ----------- |
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35 | |
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36 | Outliers widget first computes distances between each pair of examples in input |
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37 | Examples. Average distance between example to its nearest examples is valued by |
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38 | a Z-score. Z-scores higher than zero denote an example that is more distant to |
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39 | other examples than average. Input can also be a distance matrix: in this case |
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40 | precalculated distances are used. |
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41 | |
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42 | Two parameters for Z-score calculation can be choosen: distance metrics and |
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43 | number of nearest examples to which example's average distance is computed. |
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44 | Also, minimum Z-score to consider an example as outlier can be set. Note, that |
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45 | higher the example's Z-score, more distant is the example from other examples. |
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46 | |
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47 | Changes are applied automatically. |
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48 | |
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49 | .. image:: images/Outliers.gif |
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50 | :alt: Outliers |
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51 | |
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52 | Examples |
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53 | -------- |
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54 | |
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55 | Below is a simple example how to use this widget. The input is fed |
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56 | directly from the :ref:`File` widget, and the output Examples with Z-score |
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57 | to the :ref:`Data Table` widget. |
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58 | |
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59 | .. image:: images/Outliers-Example1.gif |
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60 | :alt: Schema with Outliers |
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61 | |
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