# What is knnsearch in matlab?

## What is knnsearch in matlab?

Idx = knnsearch( X , Y ) finds the nearest neighbor in X for each query point in Y and returns the indices of the nearest neighbors in Idx , a column vector. For example, you can specify the number of nearest neighbors to search for and the distance metric used in the search.

## How to use knnsearch?

Breaking it Down – Pseudo Code of KNN

1. Calculate the distance between test data and each row of training data.
2. Sort the calculated distances in ascending order based on distance values.
3. Get top k rows from the sorted array.
4. Get the most frequent class of these rows.
5. Return the predicted class.

What is Knn search?

k-nearest neighbor search identifies the top k nearest neighbors to the query. This technique is commonly used in predictive analytics to estimate or classify a point based on the consensus of its neighbors. k-nearest neighbor graphs are graphs in which every point is connected to its k nearest neighbors.

### How do kd trees work?

A K-D Tree(also called as K-Dimensional Tree) is a binary search tree where data in each node is a K-Dimensional point in space. In short, it is a space partitioning(details below) data structure for organizing points in a K-Dimensional space.

### What is the purpose of KNN?

The k-nearest neighbors (KNN) algorithm is a simple, easy-to-implement supervised machine learning algorithm that can be used to solve both classification and regression problems.

What is Knn used for?

#### How do I find my nearest Neighbour?

Here is step by step on how to compute K-nearest neighbors KNN algorithm:

1. Determine parameter K = number of nearest neighbors.
2. Calculate the distance between the query-instance and all the training samples.
3. Sort the distance and determine nearest neighbors based on the K-th minimum distance.