how do i make function in python that check if the lists is vector

Question

I have an task to Implement a function parallel_vec(lst1, lst2) with 2 arguments lst1 and lst2 that are lists of length n which represent two vectors.

The function will return True if the vectors are "parallel" otherwise False .

Definition of parallel vectors : two vectors v1 = (n1, n2, n3) and v2 = (k1, k2, k3) are parallel vectors if the ratio between all components is the same, which is defined as n1 / k1 = n2 / k2 = n3 / k3

This is what I wrote:

lst1 = [1,3,4]
lst2 = [2,6,8]
ind1 = 0 
ind2 = 1
while ind2 < len(lst1): 
    if (lst1[ind1]/lst2[ind1]) == (lst1[ind2]/lst2[ind2]):
        ind1 += 1
        ind2 += 1
        continue
        print(True)
    #return True
    else:
        print(False)

I didn't function it yet because I wanted to check if its work but it doesn't. What am I doing wrong?

Answer 1

Create a list of the fractions n1/k1, n2/k2, n3/k3

>>> [1.0, 1.0, 1.0]

Then use set to remove duplicates (this means the ratios are the same)

Then if this new list length is == to one, the vector is parallel

lst1 = [1,3,4]
lst2 = [2,6,8]

vect = [(x/y) for x,y in zip(lst1,lst1)]

if len(set(vect)) == 1:
    print(True)

else:
    print(False)

Answer 2

You must remove 'continue' from while loop in order to print(True) works . Your code:

lst1 = [1,3,4]
lst2 = [2,6,8]
ind1 = 0 
ind2 = 1
while ind2 < len(lst1): 
    if (lst1[ind1]/lst2[ind1]) == (lst1[ind2]/lst2[ind2]):
        ind1 += 1
        ind2 += 1
        print(True)
    #return True
    else:
        print(False)

My suggestion for the problem is to use numpy, like below:

import numpy as np
n1=np.array(lst1)
n2=np.array(lst2)

print(len(set(n1/n2))==1)

which actually checks if all fractions are equal

Answer 3

PseudoCode

First check if your lists contain a 0. If so, the lists aren't parallel .

If they don't have zeroes, go through the loop.

lst1 = [1,3,4]
lst2 = [2,6,8]


def parallel(lst1,lst2):
    k_factor = lst1[0]/lst2[0]

    for i,j in zip(lst1[1:],lst2[1:]):
        if i/j != k_factor:
            return print("Vectors aren't parrallel")
    return print("Vectors are parallel")


parallel(lst1,lst2)

My algorithm needs a check for null values, otherwise it will throw an error.