Python: closest coordinate?

Question

I need help with a function that returns coordinate from a list of coordinates, that\'s closest to some point. For example: closest((9, 2), {(0, 0), (10, 0), (10, 10)}

Answer 1

from math import sqrt

def euqli_dist(p, q, squared=False):
    # Calculates the euclidean distance, the "ordinary" distance between two
    # points
    # 
    # The standard Euclidean distance can be squared in order to place
    # progressively greater weight on objects that are farther apart. This
    # frequently used in optimization problems in which distances only have
    # to be compared.
    if squared:
        return ((p[0] - q[0]) ** 2) + ((p[1] - q[1]) ** 2)
    else:
        return sqrt(((p[0] - q[0]) ** 2) + ((p[1] - q[1]) ** 2))

def closest(cur_pos, positions):
    low_dist = float('inf')
    closest_pos = None
    for pos in positions:
        dist = euqli_dist(cur_pos,pos)
        if dist < low_dist:
            low_dist = dist
            closest_pos = pos
    return closest_pos

print closest((9, 2), {(0, 0), (10, 0), (10, 10)})

Output:

(10, 0)

If my math is not wrong. ;)

I'm using this formula