Declare Missing Value

Synopsis

This operator declares the specified values of the selected attributes as missing values.

Description

The Declare Missing Value operator replaces the specified values of the selected attributes by Double.NaN, thus these values will become missing values. These values will be treated as missing values by the subsequent operators. The desired values can be selected through nominal, numeric or regular expression mode. This behavior can be controlled by themodeparameter.

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

The specified values of the selected attributes are replaced by missing values 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.

Parameters

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 (正则表达式,使用除了表达) 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 examplerealandintegertypes both belong to thenumerictype. Users should have a basic understanding of type hierarchy when selecting attributes through this option. When it 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 thevalue typeoption. 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 ofattributeparameter 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 theedit and preview regular expressionmenu. 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

如果启用,异常的类型可以选择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 theregular expressionparameter).

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

如果启用,异常的类型可以选择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 typeparameter'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.

Mode

This parameter specifies the type of the value that should be set to missing value. The type can be nominal or numeric or it can be specified through a regular expression.

Numeric value

This parameter specifies the numerical value that should be declared as missing value.

Nominal value

This parameter specifies the nominal value that should be declared as missing value.

Expression value

This parameter specifies the value that should be declared as missing value through an expression.