Python: Calculating the distance between points in an array

Question

I would like to calculate the distance between data points in an array.

Example

A1 = array([[ 54.        ,  15.        ,   1.        ],
       [ 55.        ,  13.66311896,   1.        ],
       [ 56.        ,  10.16311896,   1.95491503],
       [ 57.        ,   5.83688104,   4.45491503],     # shape 6rows x 3 col
       [ 58.        ,   2.33688104,   7.54508497],
       [ 59.        ,   1.        ,  10.04508497],
       [ 60.        ,   1.        ,  11.        ],

Now, I want to calculate the distance between points in column 1 & column 2. and all the distance should be calculated from Row 0 ie.,(x1,y1 = 15,1) but x2,y2 is variable changing from elements row 1 to row6. And I want save this distance as a 'list'. Please help me in solving this in python

Please post your minimal reproducible example here. If you tell us what you have tried so far and which errors or problems you are getting, it would be much easier for us to help you. — Muhammad Mohsin Khan
– Muhammad Mohsin Khan, Commented Jan 17, 2022 at 13:21
dist_matrix = ((A1.reshape(N_points_in_A1, 1, dim_of_point) - A2.reshape(1, N_points_in_A2, dim_of_points))**2).sum(2)**0.5. dist_matrix[i, j] will contain the distance of point i in A1 form point j in A2 — yann ziselman
– yann ziselman, Commented Jan 17, 2022 at 13:26
Thanks for your comment @ yann . Could you please explain what is dim_of_points & sum(2) in ((A1.reshape(N_points_in_A1, 1, dim_of_point) - A2.reshape(1, N_points_in_A2, dim_of_points))**2).sum(2)**0.5. dist_matrix[i, j] — Akhilesh Arkala
– Akhilesh Arkala, Commented Jan 17, 2022 at 13:36
Does this answer your question? How to do n-D distance and nearest neighbor calculations on numpy arrays — Daniel F
– Daniel F, Commented Jan 17, 2022 at 13:53

Regretful · Accepted Answer · 2022-01-17 13:48:54Z

1

Pythagoras theorem states sqrt(a^2+b^2)=c where c is the distance between the tips of the orthogonal lines reaching point a and b.

import math
from math import sqrt
dist_list=[]
for i in A1[1:]:
    dist=sqrt(pow(A1[0][1]-i[1],2)+pow(A1[0][2]-i[2],2))
    dist_list.append(dist)

If you dont want to import math:

for i in A1[1:]:
    dist=pow(pow(A1[0][1]-i[1],2)+pow(A1[0][2]-i[2],2),0.5)
    dist_list2.append(dist)

answered Jan 17, 2022 at 13:48

Regretful

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