Calculate the difference between two compass headings Python

Question

I have to test whether the difference in degrees between a compass reading and a set point is within x amount.

This post describes what I'm after, it's just in C# and I can't interpret how the solution would work.

E.g...

Compass Reading  Set Point  Difference (absolute)
360              1          1
50               60         10
1                360        1

I'd encourage you to try and translate the C# solution to Python yourself, and ask concrete question if and when you get stuck, posting the code you have so far. Right now the question reads as a "please code this up for me", which generally isn't a good fit for this site. — NPE, Aug 13 '17 at 11:13

score 2 · Accepted Answer · answered Aug 13 '17 at 11:52

this is translated code to python:

def getHeadingError(init, final):
    if init > 360 or init < 0 or final > 360 or final < 0:
        raise Exception("out of range")
    diff = final - init
    absDiff = abs(diff)

    if absDiff == 180:
        return absDiff
    elif absDiff < 180:
        return diff
    elif final > init:
        return absDiff - 360
    else:
        return 360 - absDiff

print("init -- final -- error")
print("360 -- 1 -- {}".format(getHeadingError(360, 1)))
print("50 -- 60 -- {}".format(getHeadingError(50, 60)))
print("1 -- 360 -- {}".format(getHeadingError(1, 360)))

i hope this can help you

score 0 · Answer 2 · answered Dec 20 '22 at 01:27

The accepted answer works, but if you want a single return, the following will get the job done, too:

def get_compass_diff(current, target):
    diff = (current - 360) if current > 180 else current
    target = target - diff
    return target if target < 180 else target - 360

(and then if you need abs, just use abs where appropriate rather than baking it into your compass heading diff function)

Calculate the difference between two compass headings Python

2 Answers2