|  | ## Map

#### Synopsis

Maps certain values of an attribute to other values.

#### Description

This operator takes an `ExampleSet` as input and maps the values of certain attributes to other values. The operator can replace nominal values (e.g. replace the value "green" by the value "green_color") as well as numerical values (e.g. replace the all values "3" by "-1"). A single mapping can be specified using the parameters `replace_what` and `replace_by`. Multiple mappings can be specified in the parameter list `value_mappings`.

Additionally, the operator allows to define (and consider) a default mapping. If `add_default_mapping` is set to true and `default_value` is properly set, all values that occur in the example set but are not listed in the value mappings list are replaced by the default value. This may be helpful in cases where only some values should be mapped explicitly and many unimportant values should be mapped to a default value (e.g. "other").

If the parameter `consider_regular_expressions` is enabled, the values are replaced by the new values if the original values match the given regular expressions. The value corresponding to the first matching regular expression in the mappings list is taken as replacement.

This operator supports regular expressions for the attribute names, i.e. the value mapping is applied on all attributes for which the name fulfills the pattern defined by the name expression.

#### Input

- example set input: expects: ExampleSetMetaData: #examples: = 0; #attributes: 0

#### Output

- example set output:
- original:

#### Parameters

- attribute filter type: The condition specifies which attributes are selected or affected by this operator.
- attribute: The attribute which should be chosen.
- attributes: The attribute which should be chosen.
- regular expression: A regular expression for the names of the attributes which should be kept.
- use except expression: If enabled, an exception to the specified regular expression might be specified. Attributes of matching this will be filtered out, although matching the first expression.
- except regular expression: A regular expression for the names of the attributes which should be filtered out although matching the above regular expression.
- value type: The value type of the attributes.
- use value type exception: If enabled, an exception to the specified value type might be specified. Attributes of this type will be filtered out, although matching the first specified type.
- except value type: Except this value type.
- block type: The block type of the attributes.
- use block type exception: If enabled, an exception to the specified block type might be specified.
- except block type: Except this block type.
- numeric condition: Parameter string for the condition, e.g. '>= 5'
- invert selection: Indicates if only attributes should be accepted which would normally filtered.
- include special attributes: Indicate if this operator should also be applied on the special attributes. Otherwise they are always kept.
- value mappings: The value mappings.
- replace what: All occurrences of this value will be replaced.
- replace by: The new attribute value to use.
- consider regular expressions: Enables matching based on regular expressions; original values may be specified as regular expressions.
- add default mapping: If set to true, all original values which are not listed in the value mappings list are mapped to the default value.
- default value: The default value all original values are mapped to, if add_default_mapping is set to true.

#### ExampleProcess