closest-points

问题 I am trying to implement the closest pair problem in Python using divide and conquer, everything seems to work fine except that in some input cases, there is a wrong answer. My code is as follows: def closestSplitPair(Px,Py,d): X = Px[len(Px)-1][0] Sy = [item for item in Py if item[0]>=X-d and item[0]<=X+d] best,p3,q3 = d,None,None for i in xrange(0,len(Sy)-2): for j in xrange(1,min(7,len(Sy)-1-i)): if dist(Sy[i],Sy[i+j]) < best: best = (Sy[i],Sy[i+j]) p3,q3 = Sy[i],Sy[i+j] return (p3,q3,best

问题 I am trying to implement the closest pair problem in Python using divide and conquer, everything seems to work fine except that in some input cases, there is a wrong answer. My code is as follows: def closestSplitPair(Px,Py,d): X = Px[len(Px)-1][0] Sy = [item for item in Py if item[0]>=X-d and item[0]<=X+d] best,p3,q3 = d,None,None for i in xrange(0,len(Sy)-2): for j in xrange(1,min(7,len(Sy)-1-i)): if dist(Sy[i],Sy[i+j]) < best: best = (Sy[i],Sy[i+j]) p3,q3 = Sy[i],Sy[i+j] return (p3,q3,best

问题 I am trying to implement the closest pair problem in Python using divide and conquer, everything seems to work fine except that in some input cases, there is a wrong answer. My code is as follows: def closestSplitPair(Px,Py,d): X = Px[len(Px)-1][0] Sy = [item for item in Py if item[0]>=X-d and item[0]<=X+d] best,p3,q3 = d,None,None for i in xrange(0,len(Sy)-2): for j in xrange(1,min(7,len(Sy)-1-i)): if dist(Sy[i],Sy[i+j]) < best: best = (Sy[i],Sy[i+j]) p3,q3 = Sy[i],Sy[i+j] return (p3,q3,best

问题 I am given a list of integers/floats and I need to find the two numbers closest together. How would I do that using only nested for loops? 回答1: For each element, you have to compare the distance of it to each of the other elements with your previous "closest" value - any time this comparison yields smaller values, you remember that pair as the "two closest" ones. So, it is straightforward: def find_two_closest(numbers): # most distant points: delta = max(numbers), min(numbers) for i, element

问题 If I am given a list of integers/floats, how would I find the two closest numbers using sorting? 回答1: Such a method will do what you want: >>> def minDistance(lst): lst = sorted(lst) index = -1 distance = max(lst) - min(lst) for i in range(len(lst)-1): if lst[i+1] - lst[i] < distance: distance = lst[i+1] - lst[i] index = i for i in range(len(lst)-1): if lst[i+1] - lst[i] == distance: print lst[i],lst[i+1] In the first for loop we find out the minimum distance, and in the second loop, we print

问题 I have a 2 dimensional array: MyArray = array([6588252.24, 1933573.3, 212.79, 0, 0], [6588253.79, 1933602.89, 212.66, 0, 0], etc...) The first two elements MyArray[0] and MyArray[1] are the X and Y coordinates of the points. For every element in the array, I would like to find the quickest way to return its single nearest neighbor in a radius of X units. We are assuming this is in 2D space. lets say for this example X = 6 . I have solved the problem by comparing every element to every other

问题 I have about 75 million records in a SQL Server 2008 R2 Express database. Each is a lat long corresponding to some value. The table has geography column. I am trying to find one nearest neighbor for a given latitude longitude (point). I already have a query with spatial index in place. But depending on where the record is in the database, say first quarter or last quarter, the query can take about from 3 to 30 seconds to find the nearest neighbor. I feel this can be optimized to give lot