Calculate distance from one point to all others

Question

I am working with a list of ID, X, and Y data for fire hydrant locations. I am trying to find the three closest fire hydrants for each fire hydrant in the list.

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Answer 1

Here you go. Let's say you have an input list with this format [[ID, X, Y],[ID, X, Y]].

You can simply loop through each hydrant when looping through each hydrant and calculate the min distance between them. You just need to have some variable to store the min distance for each hydrant and the ID of the closest hydrant.

import math # for sqrt calculation


def distance(p0, p1):
    """ Calculate the distance between two hydrant """
    return math.sqrt((p0[1] - p1[1])**2 + (p0[2] - p1[2])**2)


input = [[0, 1, 2], [1, 2, -3], [2, -3, 5]] # your input list of hydrant

for current_hydrant in input:  # loop through each hydrant
    min_distance = 999999999999999999999999
    closest_hydrant = 0
    for other_hydrant in input:  # loop through each other hydrant
        if current_hydrant != other_hydrant:
            curr_distance = distance(current_hydrant, other_hydrant) # call the distance function
            if curr_distance < min_distance: # find the closet hydrant
                min_distance = curr_distance
                closest_hydrant = other_hydrant[0]
    print("Closest fire hydrants to the", current_hydrant[0], "is the hydrants",
          closest_hydrant, "with the distance of", min_distance)  # print the closet hydrant

Since the distance function is not very complicated i rewrite it, you can use some other function in scipy or numpy library to get the distance.

Hope this can help ;)