# KNNRegressor

Regression with K Nearest Neighbours

KNNRegressor is a supervised machine learning algorithm for regression. In machine learning, regression can be thought of as a mapping from one space to another where both can contain continuous values. In order to make predictions, the KNNRegressor must first be `fit`

with an input DataSet of data points, each of which is paired (by means of a shared identifier) with another data point in an output DataSet.

The output DataSet used with a KNNRegressor must have only 1 dimension. For an object that can perform regression with multidimensional outputs, see the MLPRegressor.

The KNNRegressor uses an internal KDTree to find an input point’s `numNeighbours`

nearest neighbours in an input dataset. When the `weight`

parameter equals `1`

, the output returned is a weighted average of those neighbours’ values from the output DataSet (this is the default). If the `weight`

parameter is set to `0`

, the output returned is a simple average of the neighbours.

When training machine learning models, including the KNNRegressor, it could be important to test and validate the trained model. Learn more about this process at Training-Testing Split.