# k nearest neighbor regression function

43 views (last 30 days)
Farideh Jalali on 6 Nov 2013
Commented: Satadru Mukherjee on 18 Jan 2021
Hi,
What is the k nearest neighbour regression function in matalb? Is only knn classification function available?
Regards
Farideh
denny on 4 Apr 2018
i want to find it too.

wang guangyi on 17 Nov 2015
i can not find it too

Satadru Mukherjee on 10 Mar 2020
Edited: Satadru Mukherjee on 10 Mar 2020
clc
clear all
close all
x=input('Enter the x coordinates:');
y=input('Enter the y coordinates:');
z=[];
a=input('Enter the x coordinate of which , you want to predict the y value:');
k=input('Enter the k value:');
for i=1:length(x)
z=[z abs(x(i)-a)];%difference calculation
end
temp=0;
gemp=0;
for i=1:length(z)
for j=1:(length(z)-i)
if(z(j)>z(j+1))
temp=z(j);
z(j)=z(j+1);
z(j+1)=temp;
gemp=y(j);
y(j)=y(j+1);
y(j+1)=gemp;
end
end
end
tuka=0;
for i=1:k
tuka=tuka+y(i);
end
output=tuka/k

Image Analyst on 10 Mar 2020
Perhaps fitcknn()
Satadru Mukherjee on 18 Jan 2021
fitcknn is for classification , not for regression

Bechir EL HOSNI on 3 Sep 2020
Edited: Bechir EL HOSNI on 3 Sep 2020
Hi
KNN is a non parametric method used in machine learning.
We find two knid of KNN:
KNN classifier: Used in classification problem in which the ouput is a categorical variable.
KNN regression : Used in regression problem in which the output is a numerical variable.
In the context of regression problem we indentifie the first the K (Integer) nearest training points, to the observation we want to predict its output, and next we compute the average of the value of those points. The optimal value of K depend on the "Bias-Vriance tradeoff" ( a very important concept in statistic and machine learning).
Thanks.

Elaheh Shamsi on 23 Sep 2020
Hi
you can use this link to use KNN regression
this paper uses one type of KNN regression to make the QSAR model.
good luck

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