0

I have an array of 4 coordinates in each array

x0 = [1,2,3,4] #x_coordinates
y0 = [1,2,3,4] #y_coordinates

x1 = [11,12,13,14] #x_coordinates
y1 = [11,12,13,14] #y_coordinates

I would like to find the distance between the two coordinates.

distance = sqrt((x1 - x0)^2 + (y1 - y0)^2)

So, I tried

distance = math.sqrt((x1 - x0)**2 + (y1 - y0)**2)

But the error is TypeError: only length-1 arrays can be converted to Python scalars.

Isnt it possible to do an element wise operation by just using the array_variable? Or do I have to iterate it by using a for loop?

I found this as a probable answer, but looks quite complicated with numpy. calculating distance between two numpy arrays

EDIT:

Tried the following

x_dist = pow((x1 - x0), 2)
y_dist = pow((y1 - y0), 2)
dist = x_dist+y_dist
dist=dist**2
Improve this question
5
  • 1
    You cannot subtract lists in python. Consider using numpy arrays. Commented Mar 25, 2018 at 19:37
  • @DyZ : are you sure, that you cant subtract ists in python?? x1-x0 looks like a completely genuine statement. Commented Mar 25, 2018 at 19:41
  • Yes, I am sure. But are you sure that your x1 and x0 are lists? Commented Mar 25, 2018 at 19:45
  • @DyZ yes, it is.. print x0 gave me [ 413.59921265 412.74182129 411.94470215 411.37411499]. Please look at my edited answer and it gives no error anymore. so I am confused why is it working, when its not possible to subtract lists in python. Commented Mar 25, 2018 at 19:49
  • sorry its <type 'numpy.ndarray'> and not a list !! I got it now. Commented Mar 25, 2018 at 19:53

2 Answers 2

Reset to default
1

Yes, with plain python lists you have to use a loop or comprehension to do things element-wise.

It's not complicated with numpy, you just have to wrap each list in an array:

from numpy import array, sqrt

x0 = array([1, 2, 3, 4])  # x_coordinates
y0 = array([1, 2, 3, 4])  # y_coordinates

x1 = array([11, 12, 13, 14])  # x_coordinates
y1 = array([11, 12, 13, 14])  # y_coordinates

print(sqrt((x1 - x0) ** 2 + (y1 - y0) ** 2))

Here is how to do it in plain Python using a loop comprehension:

from math import sqrt

x0_list = [1, 2, 3, 4]  # x_coordinates
y0_list = [1, 2, 3, 4]  # y_coordinates

x1_list = [11, 12, 13, 14]  # x_coordinates
y1_list = [11, 12, 13, 14]  # y_coordinates

print([sqrt((x1 - x0) ** 2 + (y1 - y0) ** 2)
       for x0, y0, x1, y1 in zip(x0_list, y0_list, x1_list, y1_list)])
Improve this answer
Sign up to request clarification or add additional context in comments.

6 Comments

can you please see my edit and tell me if thats another way to do it?
@infoclogged if you're using lists, no. If you're using something else, you tell me if it works.
how do I find the type of x0? Then i will tell you. But by printing x0 and x1, they do look like a list to me..
print(type(x0)). But how did you create them?
its <type 'numpy.ndarray'>... dint know that there were so many array types.. I come from the c++ world. sorry. thanks for your answer. it works.
|
0

With out numpy, this could be used:

import math

def func(x0,x1,y0,y1):

    distance = []

    for a,b,c,d in zip(x0,x1,y0,y1):
        result = math.sqrt((b - a)**2 + (d - c)**2)
        distance.append(result)

    return distance

x0 = [1,2,3,4] #x_coordinates
y0 = [1,2,3,4] #y_coordinates

x1 = [11,12,13,14] #x_coordinates
y1 = [11,12,13,14] #y_coordinates

print(func(x0, x1, y0, y1))
Improve this answer

Comments

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.