knn

knn.py

import numpy as np
import operator
point = [0,0]
k = 3
listOfPoint=[(1,1),(1,0),(2,1),(0,-1),(2,2)]


def knn(point, k, lists):
    #create a dic to store distance for each point
    dic={}
    
    for p in lists:
        #compute the distance between each point in list and target point 
        d = dist(point, p)
        dic[p]=d
    
    res = []
    #sorted the dict by value
    sorted_dic = sorted(dic.items(), key=operator.itemgetter(1))
            
    #take the kth small point       
    for key in sorted_dic:
        if len(res) < 3:
            res.append(key[0])
    return res

#compute distance between two points    
def dist(pointA, pointB):
    pointA = np.array(pointA)
    pointB = np.array(pointB)
    return sum((pointA - pointB)**2)**0.5
    
#call the function
knn(point,k,listOfPoint)

#result
[(0, -1), (1, 0), (1, 1)]