Nearest Neighbors

knearest neighbors classification usingKd-tree search

To train ak-nearest neighbors model, use theClassification Learnerapp. For greater flexibility, train ak-nearest neighbors model usingfitcknnin the command-line interface. After training, predict labels or estimate posterior probabilities by passing the model and predictor data topredict.

Apps

Classification Learner

Train models to classify data using supervised machine learning

Functions

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Create Nearest Neighbor Model

fitcknn Fitk-nearest neighbor classifier

Create Nearest Neighbor Searcher

`ExhaustiveSearcher`	Create exhaustive nearest neighbor searcher
`KDTreeSearcher`	CreateKd-tree nearest neighbor searcher
`createns`	Create nearest neighbor searcher object

Cross-Validate

`crossval`	Cross-validatedk-nearest neighbor classifier
`kfoldEdge`	Classification edge for observations not used for training
`kfoldLoss`	Classification loss for observations not used for training
`kfoldfun`	交叉验证函数
`kfoldMargin`	Classification margins for observations not used for training
`kfoldPredict`	Predict response for observations not used for training

Measure Performance

`loss`	Loss ofk-nearest neighbor classifier
`resubLoss`	Loss ofk-nearest neighbor classifier by resubstitution
`compareHoldout`	Compare accuracies of two classification models using new data
`edge`	Edge ofk-nearest neighbor classifier
`margin`	Margin ofk-nearest neighbor classifier
`partialDependence`	Compute partial dependence
`plotPartialDependence`	Create partial dependence plot (PDP) and individual conditional expectation (ICE) plots
`resubEdge`	Edge ofk-nearest neighbor classifier by resubstitution
`resubMargin`	Margin ofk-nearest neighbor classifier by resubstitution

Classify Observations

`predict`	Predict labels usingk-nearest neighbor classification model
`resubPredict`	Predict resubstitution labels ofk-nearest neighbor classifier

Related Functions

`pdist`	Pairwise distance between pairs of observations
`pdist2`	Pairwise distance between two sets of observations

Objects

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Nearest Neighbor Classification Models

`ClassificationKNN`	k-nearest neighbor classification
`ClassificationPartitionedModel`	Cross-validated classification model

Topics

Train Nearest Neighbor Classifiers Using Classification Learner App

Create and compare nearest neighbor classifiers, and export trained models to make predictions for new data.

Visualize Decision Surfaces of Different Classifiers

This example shows how to visualize the decision surface for different classification algorithms.

Supervised Learning Workflow and Algorithms

Understand the steps for supervised learning and the characteristics of nonparametric classification and regression functions.

Classification Using Nearest Neighbors

Categorize data points based on their distance to points in a training data set, using a variety of distance metrics.

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