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  5. Replace Infinite Values

(AI Studio Core)

Synopsis

This operator replaces infinite values of the selected attributes by the specified replacements.

Description

The Replace Infinite Values operator replaces positive or negative infinite values by the specified replacements. The following replacements are available: none, zero, max_byte, max_int, max_double and missing. The 'max_byte', 'max_int', 'max_double' replacements replace positive infinity by the upper bound and negative infinity by the lower bound of the range of the byte, int and double Java types respectively. If 'missing' replacement is used then the infinite values are replaced by nan (not a number), which is internally used to represent missing values. These missing values can be replenished by the Replace Missing Values operator. Different replacements can be specified for different attributes by using the columns parameter. If an attribute's name is not in the list of the columns parameter, the replacement specified by the default parameter is used.

Input

  • example set input (Data table)

    This input port expects an ExampleSet. It is the output of the Subprocess operator in the attached Example Process. The output of other operators can also be used as input. It is essential that meta data should be attached with the data for the input because attributes are specified in their meta data.

Output

  • example set output (Data table)

    The infinite values are replaced by the specified replacement and the resultant ExampleSet is output of 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 attributes in which you want to replace infinite values. 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 Parameters panel.
    • subset: This option allows selection of multiple attributes through a list. All attributes of ExampleSet are present in the list; required attributes can be easily selected. This option will not work if meta data is not known. When this option is selected another parameter becomes visible in 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 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. User should have 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 Parameters panel.
    • block type: This option is similar in working to value_type option. This option allows selection of all the attributes of a particular block type. It should be noted that block types may be hierarchical. For example value_series_start and value_series_end block types both belong to value_series block type. When this option is selected some other parameters (block type, use block type exception) become visible in 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 not selected.
    • numeric value filter: When this option is selected another parameter (numeric condition) becomes visible in Parameters panel. All numeric attributes whose all examples satisfy the mentioned numeric condition are selected. Please note that all nominal attributes are also selected irrespective of the given numerical condition.
  • attributeThe required attribute can be selected from this option. The attribute name can be selected from the drop down box of the parameter attribute if the meta data is known.
  • 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.
  • regular expressionAttributes whose name match 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 edit and preview regular expression menu. This menu gives a good idea of regular expressions. It also allows you to try different expressions and preview the results simultaneously. This will enhance your concept of regular expressions.
  • use except expressionIf enabled, an exception to the first regular expression can be specified. When this option is selected another parameter (except regular expression) becomes visible in Parameters panel.
  • 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 regular expression parameter).
  • value typeType of attributes to be selected can be chosen from drop down list.
  • use value type exceptionIf enabled, an exception to the selected type can be specified. When this option is selected another parameter (except value type) becomes visible in Parameters panel.
  • except value typeAttributes matching this type will be removed from the final output even if they matched the previously mentioned type i.e. value typeparameter's value.
  • block typeBlock type of attributes to be selected can be chosen from drop down list.
  • use block type exceptionIf enabled, an exception to the selected block type can be specified. When this option is selected another parameter (except block type) becomes visible in Parameters panel.
  • except block typeAttributes matching this block type will be removed from the final output even if they matched the previously mentioned block type.
  • numeric conditionNumeric condition for testing examples of numeric attributes is mention 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.
  • 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 removed prior to selection of this parameter. After selection of this parameter 'att1' will be removed and 'att2' will be selected.
  • include special attributesSpecial 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. By default all special attributes are delivered to the output port irrespective of the conditions in the Select Attributes operator. If this parameter is set to true, Special attributes are also tested against conditions specified in the Select Attributes operator and only those attributes are selected that satisfy the conditions.
  • defaultThis parameter specifies the replacement to apply to all attributes that are not explicitly specified by the columns parameter. The following options are available: none, zero, max_byte, max_int, max_double, missing, value.
  • columnsDifferent attributes can be provided with different types of replacements through this parameter. The default replacement selected by the default parameter is applied on attributes that are not explicitly mentioned in the columns parameter
  • replenish whatThis parameter specifies if positive or negative infinity values should be replaced.
  • replenishment valueThis parameter is only available when the default parameter is set to 'value'. This value will be inserted instead of infinity.

Tutorial Processes

Replacing infinite values by missing values

This Example Process starts with the Subprocess operator which delivers an ExampleSet. A breakpoint is inserted here so that you can have a look at the ExampleSet. Have a look at the Ratio attribute of the ExampleSet. You will see that it has a positive infinity value in the first example. The Replace Infinite Values operator is applied on this ExampleSet to replace infinite values by missing values. The default parameter is set to 'missing' and all other parameters are used with default values. You can see the resultant ExampleSet in the Results Workspace. You can see that the infinite values of the Ratio attribute have been replaced by missing values. These missing values can be replenished by using operators like the Replace Missing Values operator.

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