TypeError while trying to implement KNN algorithm with python

Question

import csv  
import random  
import math  
import operator  



def loadDataset(filename,trainingSet=[],testSet=[]):  
    with open(filename, 'rt') as csvfile:  
        lines = csv.reader(csvfile)  
        dataset = list(lines)  
        z = len(dataset)-1  


 for x in range(len(dataset)-2):  
            for y in range(8,9):  
                dataset[x][y] = float (dataset[x][y])   
                trainingSet.append(dataset[x]) 


    for y in range(8,9):  
            dataset[z][y] = float (dataset[z][y])  
            testSet.append(dataset[z])


def euclideanDistance(instance1, instance2):  
    distance = 0  
    X= (instance1[9] - instance2[9]) +(instance1[8] - instance2[8])  
    distance += pow(X, 2)  
    return math.sqrt(distance)   

def getNeighbors(trainingSet, testInstance, k):  
    distances = []  
    for x in range(len(trainingSet)):  
        dist = euclideanDistance(testInstance, trainingSet[x])  
        distances.append((trainingSet[x], dist))  
    distances.sort(key=operator.itemgetter(1))  
    neighbors = []    
    for x in range(k): 
        neighbors.append(distances[x][0])  
    return neighbors  

def main():  
    trainingSet=[]  
    testSet=[]  
    loadDataset('G:\ABCD.csv', trainingSet, testSet)  
    print ('Train set: ' + repr(len(trainingSet)))  
    print ('Test set: ' + repr(len(testSet)))  
    k = 4     
    neighbors = getNeighbors(trainingSet, testSet[0], k)  
    a=(neighbors[0][1])  
    print('Best Neighbor is: ' + a)  

main()

Error I am getting Dataset Screenshot

I am getting TypeError while executing the code basically in this program i am trying to find euclidian distance from a test point to each point in the given dataset and then after sorting trying to get neighbors with least distance .

brabster · Accepted Answer · 2018-04-25 18:38:59Z

1

The error says you are trying to subtract a string from a string (line 22 in your euclidianDistance function)

You need to parse the two co-ordinates into numbers to be able to subtract them. The float function will be able to do that.

Example - you're using instance1[9] which is a string representing a floating point number, so float(instance1[9]) should give you a number.

Just leave a comment if you're still struggling and I'll show you the update you need to make.

edited Apr 25, 2018 at 18:38

answered Apr 25, 2018 at 18:32

brabster

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1 Comment

brabster Over a year ago

You are welcome. Looks like you're new here, in case you don't know - question askers will typically click the "accept" checkmark on the answer that solved their problem to show others which answer helped (and gives the person who answered some reputation)

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