从角度数组顺时针和逆时针获取最接近的角度

Question

我从原点有四个角度的 div 角，假设 θ 与这些角度比较，我还有一个新角度，现在我需要逆时针和顺时针最接近 θ 的角度。θ = -26 // new anglea = [-15, 15, -165, -195]; // array of anglesanticlockangle = ? // closest angle anticlockwise to θ from arrayclockangle = ? // closest angle clockwise to θ from array

Answer 1

在我看来，这是最优化的解决方案。我们按顺序对数组进行排序，然后根据 find 和我们的条件查找数组的下一个值。

const θ = 90 // new angle

let a = [-15, 15, -165, -195]; // array of angle

a.sort((a, b) => a-b);

let anticlockangle;

for (i = θ; i > -360; i -= 1) {

  if (a.find(element => element === i)) {

    anticlockangle = i;

    break;

  }

}

if (anticlockangle === undefined) {

 anticlockangle = a[a.length - 1]; 

}

let clockangle;

for (i = θ; i < 360; i += 1) {

  if (a.find(element => element === i)) {

    clockangle = i;

    break;

  }

}

if (clockangle === undefined) {

  clockangle = a[0];

}

console.log(anticlockangle);

console.log(clockangle);

Answer 2

好的，根据 ag-dev 在修订历史中的第一个答案，我想出了以下内容，

θ = -26 // new angle

a = [-15, 15, -165, -195]; // array of angles

anticlockangle = getClosestAngle(θ,a,false);

clockangle = getClosestAngle(θ,a,true);

console.log(anticlockangle);

console.log(clockangle);

 function getClosestAngle(θ, arr, is_clock) {

    arr.sort();

    return is_clock ? arr.find(element => element < θ) : arr.find(element => element > θ);

  }

Answer 3

我的解决方案考虑了环绕并适用于任何角度。即使输入范围超出标准范围 0°...360° 和 -180° ... +180°（就像示例中的 -195 值一样）或者如果值是浮点数而不是整数。我现在修复了程序并用适当的 javascript 编写了它 - 并在https://playcode.io/上对其进行了测试

θi = -26;

ai = [-15, 15, -165, -195];

// loop test: ai = [-161.5, -82.6, +53.7, +174.8]; // array of angles

a = [0, 0, 0, 0]

for (i = 0; i < ai.length; i++)

{

    a[i] = getValueBetween0And360(ai[i]);

}

console.log(`a = ${ai} (${a})`);

// loop test: for(θi = -400; θi <= +400; θi += 33.3) // new angle

{

    θ = getValueBetween0And360(θi);

    //console.log(`θi = ${θi}, θ = ${θ}`);

    

    

    ccw = ai[getIndexOfNearestAngle(a, θ, -1)]; // closest angle anticlockwise to θ from array

    cw = ai[getIndexOfNearestAngle(a, θ, +1)]; // closest angle clockwise to θ from array

    console.log(`θ = ${θi.toFixed(1)} (${θ.toFixed(1)}),\tccw = ${ccw.toFixed(1)} (${getValueBetween0And360(ccw).toFixed(1)}),\tcw = ${cw.toFixed(1)} (${getValueBetween0And360(cw).toFixed(1)})`);

}

function getValueBetween0And360(input)

{

    if (input < 0)

    {

        return (input + (Math.trunc(-input / 360) + 1.0) * 360.0) % 360.0;

    }

    return input % 360.0;

}

function getValueBetweenPlusMinus180(input)

{

    in360 = getValueBetween0And360(input);

    return 180 < in360

             ? in360 - 360

             : in360;

}

// sign = +1 for clock wise (cw), -1 for counter clock wise (ccw)

// starting from angle θ towards found angle in array a

function getIndexOfNearestAngle(a, θ, sign)

{

    var iF = -1;

    var diffF = 1000;

    for (var i = 0; i < a.length; i++)

    {

        var diff = sign * getDiffClockWise(a[i], θ);

        var diffPos = getValueBetween0And360(diff);

        //console.log(`start a[${i}] = ${a[i]}, diffPos = ${diffPos}, iF = ${iF}, diffF = ${diffF}, sign = ${sign}`);

        

        if (diffPos < diffF)

        {

            diffF = diffPos;

            iF = i;

        }

        //console.log(`end   a[${i}] = ${a[i]}, diffPos = ${diffPos}, iF = ${iF}, diffF = ${diffF}`);

    }

    

    return iF;

}

 

function getDiffClockWise(a, θ)

{

    //console.log(`diff = ${a - θ}, a = ${a}, θ = ${θ}`)

    return a - θ;

}

结果是：

a = -15,15,-165,-195 (345,15,195,165)

θ = -26.0 (334.0),  ccw = -165.0 (195.0),   cw = -15.0 (345.0)

如果// loop test:在代码中没有替换，它会报告这些示例显示环绕和浮动工作：

a = -161.5,-82.6,53.7,174.8 (198.5,277.4,53.7,174.8)

θ = -400.0 (320.0), ccw = -82.6 (277.4),    cw = 53.7 (53.7)

θ = -366.7 (353.3), ccw = -82.6 (277.4),    cw = 53.7 (53.7)

θ = -333.4 (26.6),  ccw = -82.6 (277.4),    cw = 53.7 (53.7)

θ = -300.1 (59.9),  ccw = 53.7 (53.7),  cw = 174.8 (174.8)

θ = -266.8 (93.2),  ccw = 53.7 (53.7),  cw = 174.8 (174.8)

θ = -233.5 (126.5), ccw = 53.7 (53.7),  cw = 174.8 (174.8)

θ = -200.2 (159.8), ccw = 53.7 (53.7),  cw = 174.8 (174.8)

θ = -166.9 (193.1), ccw = 174.8 (174.8),    cw = -161.5 (198.5)

θ = -133.6 (226.4), ccw = -161.5 (198.5),   cw = -82.6 (277.4)

θ = -100.3 (259.7), ccw = -161.5 (198.5),   cw = -82.6 (277.4)

θ = -67.0 (293.0),  ccw = -82.6 (277.4),    cw = 53.7 (53.7)

θ = -33.7 (326.3),  ccw = -82.6 (277.4),    cw = 53.7 (53.7)

θ = -0.4 (359.6),   ccw = -82.6 (277.4),    cw = 53.7 (53.7)

θ = 32.9 (32.9),    ccw = -82.6 (277.4),    cw = 53.7 (53.7)

θ = 66.2 (66.2),    ccw = 53.7 (53.7),  cw = 174.8 (174.8)

θ = 99.5 (99.5),    ccw = 53.7 (53.7),  cw = 174.8 (174.8)

θ = 132.8 (132.8),  ccw = 53.7 (53.7),  cw = 174.8 (174.8)

θ = 166.1 (166.1),  ccw = 53.7 (53.7),  cw = 174.8 (174.8)

θ = 199.4 (199.4),  ccw = -161.5 (198.5),   cw = -82.6 (277.4)

θ = 232.7 (232.7),  ccw = -161.5 (198.5),   cw = -82.6 (277.4)

θ = 266.0 (266.0),  ccw = -161.5 (198.5),   cw = -82.6 (277.4)

θ = 299.3 (299.3),  ccw = -82.6 (277.4),    cw = 53.7 (53.7)

θ = 332.6 (332.6),  ccw = -82.6 (277.4),    cw = 53.7 (53.7)

θ = 365.9 (5.9),    ccw = -82.6 (277.4),    cw = 53.7 (53.7)

θ = 399.2 (39.2),   ccw = -82.6 (277.4),    cw = 53.7 (53.7)

Answer 4

这不是最佳解决方案，但这样的事情应该会让你接近：

const theta = -26

const angles = [-15, 15, -165, -195]

let lowestAngle = null

let highestAngle = null

let previousAngle = null

let nextAngle = null

for (let index = 0; index < a.length; index++) {

  const angle = angles[index]

  if (lowestAngle === null || angle < lowestAngle) {

    lowestAngle = angle

  }

  if (highestAngle === null || angle > highestAngle) {

    highestAngle = angle

  }

  if (angle < theta) {

    // If this is the first angle less than theta or if this angle is closer to theta than the current previous, save it

    if (previousAngle === null || angle > previousAngle) {

      previousAngle = angle

    }

  }

  else if (angle > theta) {

    // If this is the first angle greater than theta or if this angle is closer to theta than the current next, save it

    if (nextAngle === null || angle < nextAngle) {

      nextAngle = angle

    }

  }

  else {

    // angle matches theta...what do you want to do here?

  }

}

// No previous angle found; loop around to the highest angle

if (previousAngle === null) {

  previousAngle = highestAngle

}

// No next angle found; loop around to the lowest angle

if (nextAngle === null) {

  nextAngle = lowestAngle

}