Linear Regression
=================
A linear regression algorithm with optional L1 (LASSO), L2 (ridge) or L1L2 (elastic net) regularization.
**Inputs**
- Data: input dataset
- Preprocessor: preprocessing method(s)
**Outputs**
- Learner: linear regression learning algorithm
- Model: trained model
- Coefficients: linear regression coefficients
The **Linear Regression** widget constructs a learner/predictor that learns a [linear function](https://en.wikipedia.org/wiki/Linear_regression) from its input data. The model can identify the relationship between a predictor xi and the response variable y. Additionally, [Lasso](https://en.wikipedia.org/wiki/Least_squares#Lasso_method) and [Ridge](https://en.wikipedia.org/wiki/Least_squares#Lasso_method) regularization parameters can be specified. Lasso regression minimizes a penalized version of the least squares loss function with L1-norm penalty and Ridge regularization with L2-norm penalty.
Linear regression works only on regression tasks.
![](images/LinearRegression-stamped.png)
1. The learner/predictor name
2. Choose a model to train:
- no regularization
- a [Ridge](https://en.wikipedia.org/wiki/Least_squares#Lasso_method) regularization (L2-norm penalty)
- a [Lasso](https://en.wikipedia.org/wiki/Least_squares#Lasso_method) bound (L1-norm penalty)
- an [Elastic net](https://en.wikipedia.org/wiki/Elastic_net_regularization) regularization
3. Produce a report.
4. Press *Apply* to commit changes. If *Apply Automatically* is ticked, changes are committed automatically.
Example
-------
Below, is a simple workflow with *housing* dataset. We trained **Linear Regression** and [Random Forest](../model/randomforest.md) and evaluated their performance in [Test & Score](../evaluation/testandscore.md).
![](images/LinearRegression-regression.png)