在Python中计算两个向量之间的角度 [英] Calculating angle between two vectors in python

问题描述

我正在尝试在python中计算两条线之间的角度. 我搜索了互联网，找到了如何做的方程式.但是我并不总是能得到准确的结果.当其他结果似乎正确时，其中一些结果显然是错误的. 我的代码如下:

I am trying to calculate the angle between two lines in python. I searched the internet and found the equation on how to do it. But I don't always get accurate result. Some of the results are clearly false when other seems correct. My code is given below:

def angle(pt1,pt2):
    m1 = (pt1.getY() - pt1.getY())/1
    m2 = (pt2.getY() - pt1.getY())/(pt2.getX()-pt1.getX())

    tnAngle = (m1-m2)/(1+(m1*m2))
    return math.atan(tnAngle)

def calculate(pt,ls):
    i=2
    for x in ls:
        pt2 = point(x,i)
        i=i+1
        ang = angle(pt,pt2)*180/math.pi
        ang = ang * (-1)
        print ang


pt = point(3,1)
ls = [1,7,0,4,9,6,150]

calculate(pt,ls)

它产生的结果是:

45.0
0.0
45.0
-75.9637565321
0.0
-63.4349488229
0.0

问题在于，我不明白为什么第二个结果(第五个和最后一个结果)被归零，因为它们共享一个点，而另一个点却不重复，因为数组中的值不同.

The problem is that I don't understand why the second result, fifth and the last one are zeroed they intersect since they share a point and the other point in not duplicated since the value in the array is different.

推荐答案

看起来您正在使用Python2，如果两个参数都为int，则/将执行整数除法.要获得Python3的行为，您可以将其放在文件顶部

It looks like you are using Python2, where / will do an integer division if both arguments are int. To get the behaviour that Python3 has, you can put this at the top of the file

from __future__ import division

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