# OlsTrainer Class

## Definition

The IEstimator<TTransformer> for training a linear regression model using ordinary least squares (OLS) for estimating the parameters of the linear regression model.

`public sealed class OlsTrainer : Microsoft.ML.Trainers.TrainerEstimatorBase<Microsoft.ML.Data.RegressionPredictionTransformer<Microsoft.ML.Trainers.OlsModelParameters>,Microsoft.ML.Trainers.OlsModelParameters>`

```
type OlsTrainer = class
inherit TrainerEstimatorBase<RegressionPredictionTransformer<OlsModelParameters>, OlsModelParameters>
```

```
Public NotInheritable Class OlsTrainer
Inherits TrainerEstimatorBase(Of RegressionPredictionTransformer(Of OlsModelParameters), OlsModelParameters)
```

- Inheritance

## Remarks

To create this trainer, use Ols or Ols(Options).

### Input and Output Columns

The input label column data must be Single. The input features column data must be a known-sized vector of Single.

This trainer outputs the following columns:

Output Column Name | Column Type | Description |
---|---|---|

`Score` |
Single | The unbounded score that was predicted by the model. |

### Trainer Characteristics

Machine learning task | Regression |

Is normalization required? | Yes |

Is caching required? | No |

Required NuGet in addition to Microsoft.ML | Microsoft.ML.Mkl.Components |

### Training Algorithm Details

Ordinary least squares (OLS) is a parameterized regression method. It assumes that the conditional mean of the dependent variable follows a linear function of the dependent variables. The regression parameters can be estimated by minimizing the squares of the difference between observed values and the predictions

Check the See Also section for links to usage examples.

## Fields

FeatureColumn |
The feature column that the trainer expects. (Inherited from TrainerEstimatorBase<TTransformer,TModel>) |

LabelColumn |
The label column that the trainer expects. Can be |

WeightColumn |
The weight column that the trainer expects. Can be |

## Properties

Info |

## Methods

Fit(IDataView) |
Trains and returns a ITransformer. (Inherited from TrainerEstimatorBase<TTransformer,TModel>) |

GetOutputSchema(SchemaShape) | (Inherited from TrainerEstimatorBase<TTransformer,TModel>) |

## Extension Methods

WithOnFitDelegate<TTransformer>(IEstimator<TTransformer>, Action<TTransformer>) |
Given an estimator, return a wrapping object that will call a delegate once Fit(IDataView) is called. It is often important for an estimator to return information about what was fit, which is why the Fit(IDataView) method returns a specifically typed object, rather than just a general ITransformer. However, at the same time, IEstimator<TTransformer> are often formed into pipelines with many objects, so we may need to build a chain of estimators via EstimatorChain<TLastTransformer> where the estimator for which we want to get the transformer is buried somewhere in this chain. For that scenario, we can through this method attach a delegate that will be called once fit is called. |

## Applies to

## See also

## Feedback

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