python - TypeError: unsupported operand type(s) for -: 'tuple' and 'tuple'

Question

I try to find Euclidean distance between csv file row elements. My csv file format is as following.

A | B | C | D

1 0 0 2

2 1 1 0

3 0 0 1

First, the user enters an input. For example, if the user enters 1 the output will be [('1', '0')]. Then, second input is taken from user to find Euclidean distance between two point. The code is as following.

import csv
from math import*


def euclidean_distance(x,y):
      return sqrt(sum(pow(a-b,2) for a, b in zip(x, y)))

with open("file1.csv") as f:
       csvr = csv.reader(f)
       csvr = list(csvr)

       f = open( 'file1.csv', 'rU' ) #open the file in read universal mode
       i = int(input("Input1: "))
       output = []
       for line in csvr[i]:
           cells = line.split( ";" )
           output.append( ( cells[ 0 ], cells[ 1 ] ) ) #since we want the first and second column

       i2 = int(input("Input2: "))
       output2 = []
       for line in csvr[i2]:
           cells = line.split( ";" )
           output2.append( ( cells[ 0 ], cells[ 1 ] ) ) #since we want the first and second column

       f.close()

       print output
       print output2
       print euclidean_distance(output,output2)

The error is as following. How can I fix it? Thanks for your advance.

 return sqrt(sum(pow(a-b,2) for a, b in zip(x, y)))
 TypeError: unsupported operand type(s) for -: 'tuple' and 'tuple'

Answer 1

Below is an example on how to calculate Euclidean distance using numpy.linalg.norm:

import numpy as np

csv = np.genfromtxt ('file1.csv', delimiter=",")

i = int(input("Input1: "))
second = csv[i,0:2]    #selects ith row and 0th & 1st columns 
i2 = int(input("Input2: "))
third = csv[i2,0:2] #selects ith row and 0th & 1st columns 

print second
print third

a=np.array(second)
b=np.array(third)
dist = np.linalg.norm(a-b)
print dist

Also note that input data looks like

A B C D
1 0 0 2
2 1 1 0
3 0 0 1

output is

Input1: 1
Input2: 2
[ 1.  0.]
[ 2.  1.]
1.41421356237