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[英]Calculating pairwise Euclidean distance of 3d points between all the rows of a dataframe
[英]Pairwise Euclidean distance from a list of points
我正在嘗試編寫一個Python函數(不使用模塊),該函數將遍歷坐標列表並查找兩個后續點之間的歐式距離(例如,點a和b,b和c,c之間的距離)和d等)。 經過幾個小時的搜索,我發現這篇文章認為可以解決我的問題,所以我寫了這樣的文章:
myList = [[2, 3], [3,4], [4,5], [5,6], [6,7]]
def distance(pointOne,pointTwo):
eucDist = ((pointOne[0] - pointTwo[0])**2 + (pointOne[1] - pointTwo[1])**2)**0.5
return eucDist
def totalDistance(inputPoints):
dist = []
for item in inputPoints[1:]:
coordDist = distance(inputPoints[0],item)
dist.append(coordDist)
return sum(dist)
print totalDistance(myList)
但是,這將檢索第一個點與其他每個點之間的距離。 我一直在嘗試找出如何為序列中的下一個點定義變量,但是我對Python還是很陌生,只是不太了解如何到達那里。 我目前正在這樣編寫totalDistance
函數:
def totalDistance(inputPoints):
dist = []
for item in inputPoints:
pOne = item
pTwo =
coordDist = distance(pOne,pTwo)
dist.append(coordDist)
return sum(dist)
但無法弄清楚如何定義pTwo。
def distance(point_one, point_two):
return ((point_one[0] - point_two[0]) ** 2 +
(point_one[1] - point_two[1]) ** 2) ** 0.5
def total_distance(points):
return sum(distance(p1, p2) for p1, p2 in zip(points, points[1:]))
或者,對於使用map
Python 3(來自注釋):
def total_distance(points):
return sum(map(distance, points, points[1:]))
my_points = [[2, 3], [3, 4], [4, 5], [5, 6], [6, 7]]
print(total_distance(my_points))
5.656854249492381
一種方法是:
def totalDistance(inputPoints):
dist = []
pTwo = inputPoints[0]
for item in inputPoints[1:]:
pOne = pTwo
pTwo = item
coordDist = distance(pOne,pTwo)
dist.append(coordDist)
return sum(dist)
基本上,記錄第一項,然后從列表中的第二項進行迭代。 最好將pOne
和pTwo
交換pOne
更好地理解,或者更清楚並使用更多Pythonic名稱:
def totalDistance(input_points):
dist = []
this_item = input_points[0]
for item in input_points[1:]:
prev_item = this_item
this_item = item
coord_dist = distance(prev_item, this_item)
dist.append(coord_dist)
return sum(dist)
使用itertools和NumPy:
from itertools import tee
import numpy as np
def pairwise(iterable):
a, b = tee(iterable)
next(b, None)
return zip(a, b)
def total_dist(points):
return np.sum(np.sqrt(np.sum(np.square(
np.diff(tuple(pairwise(points)))), axis=-2)))
total_dist(myList)
# 5.656854249492381
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