Add Noise (RapidMiner Studio Core)

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 (Data Table)
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 (Data Table)
Noise is added to the given ExampleSet and the resultant ExampleSet is delivered through this port.
original (Data Table)
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 (Preprocessing Model)
This port delivers the preprocessing model, which has information regarding the parameters of this operator in the current process.

Parameters

attribute_filter_typeThis 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.
Range: selection
attributeThe 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. Range: string
attributesThe 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. Range: string
regular_expressionThe 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. Range: string
use_except_expressionIf 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. Range: boolean
except_regular_expressionThis 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). Range: string
value_typeThe 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. Range: selection
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. Range: boolean
except_value_typeThe 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. Range: selection
block_typeThe block type of attributes to be selected can be chosen from a drop down list. The only possible value here is 'single_value' Range: selection
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. Range: boolean
except_block_typeThe attributes matching this block type will be removed from the final output even if they matched the previously mentioned block type. Range: selection
numeric_conditionThe 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. Range: string
include_special_attributesThe 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. Range: boolean
invert_selectionIf 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. Range: boolean
random_attributesThis parameter specifies the required number of new random attributes to add to the input ExampleSet. Range: integer
label_noiseThis 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. Range: real
default_attribute_noiseThis 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 Range: real
noiseThis parameter gives the flexibility of adding different noises to different attributes by providing a list of noises for all attributes. Range: list
offsetThe offset value is added to the values of all the random attributes created by this operator Range: real
linear_factorThe linear factor value is multiplied with the values of all the random attributes created by this operator Range: real
use_local_random_seedThis parameter indicates if a local random seed should be used for randomization. Range: boolean
local_random_seedThis parameter specifies the local random seed. This parameter is only available if the use local random seed parameter is set to true. Range: integer

Tutorial Processes

Adding noise to the Polynomial data set

The 'Polynomial' data set is loaded using the Retrieve operator. The Add Noise operator is applied on it. The attribute filter type parameter is set to 'all', thus noise will be added to all the attributes of the ExampleSet. The label noise and default attribute noise parameters are set to 0.05 and 0.06 respectively. The random attributes parameter is set to 1, thus a new random attribute will be added to the ExampleSet. The ExampleSet with noise and the original ExampleSet are connected to the result ports of the process. Both ExampleSets can be seen in the Results Workspace. You can see that there is a new random attribute in the ExampleSet generated by the Add Noise operator. By comparing the values of both ExampleSets you can see how noise was added by the Add Noise operator.