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Add Noise

Synopsis​

This operator adds noise in the given ExampleSet by adding random attributes to the ExampleSet and by adding noise in the existing attributes.

Description​

The Add Noise operator provides a number of parameters for selecting the attributes for adding noise in them. This operator can add noise to the label attribute or to the regular attributes separately. In case of a numerical label the given label noise (specified by the label noise parameter) is the percentage of the label range which defines the standard deviation of normal distributed noise which is added to the label attribute. For nominal labels the label noise parameter defines the probability to randomly change the nominal label value. In case of adding noise to regular attributes the default attribute noise parameter simply defines the standard deviation of normal distributed noise without using the attribute value range. Using the parameter list is also possible for setting different noise levels for different attributes (by using the noise parameter). However, it is not possible to add noise to nominal attributes.

The Add Noise operator can add random attributes to the ExampleSet. The number of random attributes is specified by the random attributes parameter. New random attributes are simply filled with random data which is not correlated to the label at all. The offset and linear factor parameters are available for adjusting the values of new random attributes.

Input​

example set input​

This input port expects an ExampleSet. It is the output of the Retrieve operator in the attached Example Process. The output of other operators can also be used as input.

Output​

example set output​

Noise is added to the given ExampleSet and the resultant ExampleSet is delivered through this port.

original​

The ExampleSet that was given as input is passed without changing to the output through this port. This is usually used to reuse the same ExampleSet in further operators or to view the ExampleSet in the Results Workspace.

preprocessing model​

This port delivers the preprocessing model, which has information regarding the parameters of this operator in the current process.

Parameters​

Attribute filter type​

This parameter allows you to select the attribute selection filter; the method you want to use for selecting the required attributes. It has the following options:

  • all: This option simply selects all the attributes of the ExampleSet. This is the default option.
  • single: This option allows selection of a single attribute. When this option is selected another parameter (attribute) becomes visible in the Parameters panel.
  • subset: This option allows selection of multiple attributes through a list. All attributes of the ExampleSet are present in the list; required attributes can be easily selected. This option will not work if the meta data is not known. When this option is selected another parameter becomes visible in the Parameters panel.
  • regular_expression: This option allows you to specify a regular expression for attribute selection. When this option is selected some other parameters (regular expression, use except expression) become visible in the Parameters panel.
  • value_type: This option allows selection of all the attributes of a particular type. It should be noted that types are hierarchical. For example ** real** and ** integer** types both belong to numeric type. Users should have a basic understanding of type hierarchy when selecting attributes through this option. When this option is selected some other parameters (value type, use value type exception) become visible in the Parameters panel.
  • block_type: This option is similar in working to the value type option. This option allows selection of all the attributes of a particular block type. When this option is selected some other parameters (block type, use block type exception) become visible in the Parameters panel.
  • no_missing_values: This option simply selects all the attributes of the ExampleSet which don't contain a missing value in any example. Attributes that have even a single missing value are removed.
  • numeric value filter: When this option is selected another parameter (numeric condition) becomes visible in the Parameters panel. All numeric attributes whose examples all satisfy the mentioned numeric condition are selected. Please note that all nominal attributes are also selected irrespective of the given numerical condition.

Attribute​

The desired attribute can be selected from this option. The attribute name can be selected from the drop down box of attribute parameter if the meta data is known.

Attributes​

The required attributes can be selected from this option. This opens a new window with two lists. All attributes are present in the left list and can be shifted to the right list which is the list of selected attributes on which the conversion from nominal to numeric will take place; all other attributes will remain unchanged.

Regular expression​

The attributes whose name matches this expression will be selected. Regular expression is a very powerful tool but needs a detailed explanation to beginners. It is always good to specify the regular expression through the edit and preview regular expression menu. This menu gives a good idea of regular expressions. This menu also allows you to try different expressions and preview the results simultaneously. This will enhance your concept of regular expressions.

Use except expression​

If enabled, an exception to the selected type can be specified. When this option is selected another parameter (except value type) becomes visible in the Parameters panel.

Except regular expression​

This option allows you to specify a regular expression. Attributes matching this expression will be filtered out even if they match the first expression (expression that was specified in the regular expression parameter).

Value type​

The type of attributes to be selected can be chosen from a drop down list. One of the following types can be chosen: nominal, text, binominal, polynominal, file_path.

Use value type exception​

If enabled, an exception to the selected type can be specified. When this option is selected another parameter (except value type) becomes visible in the Parameters panel.

Except value type​

The attributes matching this type will be removed from the final output even if they matched the previously mentioned type i.e. ** value type** parameter's value. One of the following types can be selected here: nominal, text, binominal, polynominal, file_path.

Block type​

The block type of attributes to be selected can be chosen from a drop down list. The only possible value here is 'single_value'

Use block type exception​

If enabled, an exception to the selected block type can be specified. When this option is selected another parameter (except block type) becomes visible in the Parameters panel.

Except block type​

The attributes matching this block type will be removed from the final output even if they matched the previously mentioned block type.

Numeric condition​

The numeric condition for testing examples of numeric attributes is specified here. For example the numeric condition '> 6' will keep all nominal attributes and all numeric attributes having a value of greater than 6 in every example. A combination of conditions is possible: '> 6 && < 11' or '<= 5 || < 0'. But && and || cannot be used together in one numeric condition. Conditions like '(> 0 && < 2) || (>10 && < 12)' are not allowed because they use both && and ||. Use a blank space after '>', '=' and '<' e.g. '<5' will not work, so use '< 5' instead.

Include special attributes​

The special attributes are attributes with special roles which identify the examples. In contrast regular attributes simply describe the examples. Special attributes are: id, label, prediction, cluster, weight and batch.

Invert selection​

If this parameter is set to true, it acts as a NOT gate, it reverses the selection. In that case all the selected attributes are unselected and previously unselected attributes are selected. For example if attribute 'att1' is selected and attribute 'att2' is unselected prior to checking of this parameter. After checking of this parameter 'att1' will be unselected and 'att2' will be selected.

Random attributes​

This parameter specifies the required number of new random attributes to add to the input ExampleSet.

Label noise​

This parameter specifies the noise to be added in the label attribute. In case of a numerical label the given label noise is the percentage of the label range which defines the standard deviation of normal distributed noise which is added to the label attribute. For nominal labels the label noise parameter defines the probability to randomly change the nominal label value.

Default attribute noise​

This parameter specifies the default noise for all the selected regular attributes. The default attribute noise parameter simply defines the standard deviation of normal distributed noise without using the attribute value range

Noise​

This parameter gives the flexibility of adding different noises to different attributes by providing a list of noises for all attributes.

Offset​

The offset value is added to the values of all the random attributes created by this operator

Linear factor​

The linear factor value is multiplied with the values of all the random attributes created by this operator

Use local random seed​

This parameter indicates if a local random seed should be used for randomization.

Local random seed​

This parameter specifies the local random seed. This parameter is only available if the use local random seed parameter is set to true.