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

class Point:
    def __init__(self,x,y):
        self.x = x
        self.y = y
    def closest(self,*points):           
        return min(points,key=lambda x:abs(x-self))
    def __sub__(self,other):
        return Point((self.x-other.x) , (self.y - other.y))
    def __pow__(self,powTo):
        return Point(self.x**powTo,self.y**powTo) 
    def __iter__(self):
        yield self.x
        yield self.y
    def __abs__(self):
        return sum(self**2)**0.5
    def __str__(self):
        return "(%s,%s)"%(self.x,self.y)

pt0 = Point(9,2)
print pt0.closest(Point(0,0),Point(10,0),Point(10,10))

is one way you could do it ;)

a slightly simpler way(given that you have written your dist method)

def closest(p0,otherPoints):
    def distTo(p):
        def _inner(other):
            return dist(p,other)
        return inner
    return min(otherPoints,key=distTo(p0))

or even simpler

def closest(p0,otherPoints):
    return min(otherPoints,key=lambda x:dist(p0,x))

Answer 2

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