VectorDimensionalityReduction - Vector Dimensionality Reduction
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Performs dimensionality reduction of the input vector data according to a model file.

Detailed description
--------------------

This application performs a vector data dimensionality reduction based on a model file produced by the TrainDimensionalityReduction application.

Parameters
----------

This section describes in details the parameters available for this application. Table [#]_ presents a summary of these parameters and the parameters keys to be used in command-line and programming languages. Application key is *VectorDimensionalityReduction* .

.. [#] Table: Parameters table for Vector Dimensionality Reduction.

+-------------------+-----------------------------------------------------+--------------------------+
|Parameter Key      |Parameter Name                                       |Parameter Type            |
+===================+=====================================================+==========================+
|in                 |Name of the input vector data                        |Input vector data         |
+-------------------+-----------------------------------------------------+--------------------------+
|instat             |Statistics file                                      |Input File name           |
+-------------------+-----------------------------------------------------+--------------------------+
|model              |Model file                                           |Input File name           |
+-------------------+-----------------------------------------------------+--------------------------+
|out                |Output vector data file containing the reduced vector|Output File name          |
+-------------------+-----------------------------------------------------+--------------------------+
|feat               |Input features to use for reduction.                 |List                      |
+-------------------+-----------------------------------------------------+--------------------------+
|featout            |Output feature                                       |Choices                   |
+-------------------+-----------------------------------------------------+--------------------------+
|featout prefix     |Prefix                                               | *Choice*                 |
+-------------------+-----------------------------------------------------+--------------------------+
|featout list       |List                                                 | *Choice*                 |
+-------------------+-----------------------------------------------------+--------------------------+
|featout.prefix.name|Feature name prefix                                  |String                    |
+-------------------+-----------------------------------------------------+--------------------------+
|featout.list.names |Feature name list                                    |String list               |
+-------------------+-----------------------------------------------------+--------------------------+
|pcadim             |Principal component dimension                        |Int                       |
+-------------------+-----------------------------------------------------+--------------------------+
|mode               |Writing mode                                         |Choices                   |
+-------------------+-----------------------------------------------------+--------------------------+
|mode overwrite     |Overwrite                                            | *Choice*                 |
+-------------------+-----------------------------------------------------+--------------------------+
|mode update        |Update                                               | *Choice*                 |
+-------------------+-----------------------------------------------------+--------------------------+
|inxml              |Load otb application from xml file                   |XML input parameters file |
+-------------------+-----------------------------------------------------+--------------------------+
|outxml             |Save otb application to xml file                     |XML output parameters file|
+-------------------+-----------------------------------------------------+--------------------------+

**Name of the input vector data**: The input vector data to reduce.

**Statistics file**: A XML file containing mean and standard deviation to center and reduce samples before dimensionality reduction (produced by ComputeImagesStatistics application).

**Model file**: A model file (produced by the TrainDimensionalityReduction application,.

**Output vector data file containing the reduced vector**: Output vector data file storing sample values (OGR format). If not given, the input vector data file is used. In overwrite mode, the original features will be lost.

**Input features to use for reduction.**: List of field names in the input vector data used as features for reduction.

**Output feature**: Naming of output features. Available choices are: 

- **Prefix**: Use a name prefix.

 * **Feature name prefix**: Name prefix for output features. This prefix is followed by the numeric index of each output feature.

- **List**: Use a list with all names.

 * **Feature name list**: List of field names for the output features which result from the reduction.


**Principal component dimension**: This optional parameter can be set to reduce the number of eignevectors used in the PCA model file. This parameter can't be used for other models.

**Writing mode**: This parameter determines if the output file is overwritten or updated [overwrite/update]. If an output file name is given, the original file is copied before creating the new features. Available choices are: 

- **Overwrite**: Overwrite mode.
- **Update**: Update mode.

**Load otb application from xml file**: Load otb application from xml file.

**Save otb application to xml file**: Save otb application to xml file.



Example
-------

To run this example in command-line, use the following: 
::

	otbcli_VectorDimensionalityReduction -in vectorData.shp -instat meanVar.xml -model model.txt -out vectorDataOut.shp -feat perimeter area width

To run this example from Python, use the following code snippet: 

::

	#!/usr/bin/python

	# Import the otb applications package
	import otbApplication

	# The following line creates an instance of the VectorDimensionalityReduction application 
	VectorDimensionalityReduction = otbApplication.Registry.CreateApplication("VectorDimensionalityReduction")

	# The following lines set all the application parameters:
	VectorDimensionalityReduction.SetParameterString("in", "vectorData.shp")

	VectorDimensionalityReduction.SetParameterString("instat", "meanVar.xml")

	VectorDimensionalityReduction.SetParameterString("model", "model.txt")

	VectorDimensionalityReduction.SetParameterString("out", "vectorDataOut.shp")

	# The following line execute the application
	VectorDimensionalityReduction.ExecuteAndWriteOutput()

Limitations
~~~~~~~~~~~

None

Authors
~~~~~~~

This application has been written by OTB-Team.

See Also
~~~~~~~~

These additional resources can be useful for further information: 
  | TrainDimensionalityReduction