# ITransformer Interface

## Definition

The transformer is a component that transforms data. It also supports 'schema propagation' to answer the question of 'how will the data with this schema look, after you transform it?'.

public interface ITransformer : Microsoft.ML.ICanSaveModel
type ITransformer = interface
interface ICanSaveModel
Public Interface ITransformer
Implements ICanSaveModel
Derived
Implements

## Properties

 Whether a call to GetRowToRowMapper(DataViewSchema) should succeed, on an appropriate schema.

## Methods

 Schema propagation for transformers. Returns the output schema of the data, if the input schema is like the one provided. Constructs a row-to-row mapper based on an input schema. If IsRowToRowMapper is false, then an exception should be thrown. If the input schema is in any way unsuitable for constructing the mapper, an exception should likewise be thrown. (Inherited from ICanSaveModel) Take the data in, make transformations, output the data. Note that IDataView's are lazy, so no actual transformations happen here, just schema validation.

## Extension Methods

 Preview an effect of the transformer on a given data. Create a new transformer chain, by appending another transformer to the end of this transformer chain. TimeSeriesPredictionEngine creates a prediction engine for a time series pipeline. It updates the state of time series model with observations seen at prediction phase and allows checkpointing the model. TimeSeriesPredictionFunction creates a prediction function/engine for a time series pipeline It updates the state of time series model with observations seen at prediction phase and allows checkpointing the model.