将数组的元素乘以3个权重因子，然后重复

Question

我希望能够将每个数组元素乘以3个不同的权重因子。

用户输入= [24,3,0, 56,43,34]

输出= 24x7,3x3,0x1 + 56x7, 43x3, 34x0..基本上，在数组的每3个元素上重复7的乘法，然后是3，然后是0。

它看起来像这样：

对于每个数组元素，将每个数组权重因子相乘，当达到第三个元素时重复此操作

function multiplyWeightFact(input){

 const weighting = [7,3,1]

  for (let i = 0; i < input.length ; i++) {
    console.log( input[0] * weighting[0])
    console.log( input[1] * weighting[1])
    console.log( input[3] * weighting[2])
    break
}
for (let index = 0; index < input.length; index++) {
  console.log( input[4] * weighting[0])
  console.log( input[5] * weighting[1])
  console.log( input[6] * weighting[2])
  break 
}
  }

来自用户的输入= [24,3,0, 56,43,34]

如果我们有一个数组，假设有100个数字，它就会继续。

输出需要如下所示：

resultOutput = 374 when input is [24,10]

当然，上面的功能是不可持续的，所以有没有更好的方法呢？

Answer 1

您可以通过获取一个索引和长度为weighting的余数运算符进行映射。

​

const
    multiplyBy = weighting => (v, i) => v * weighting[i % weighting.length],
    array = [24, 3, 0, 56, 43, 34],
    weighting = [7, 3, 1],
    result = array.map(multiplyBy(weighting));

console.log(...result);

​

使用x

​

const
    multiplyBy = weighting => (v, i) => `${v}x${weighting[i % weighting.length]}`,
    array = [24, 3, 0, 56, 43, 34],
    weighting = [7, 3, 1],
    result = array.map(multiplyBy(weighting));

console.log(...result);

​

Answer 2

您可以遍历数组元素，并使用模运算符根据右因数的位置与之相乘。

模数解释

计算余数。

const weighting = [7, 3, 1] // Instead of 3 weighting.length

1. 0 % 3 = 0 = Array Element = 7
2. 1 % 3 = 1 = Array Element = 3
3. 2 % 3 = 2 = Array Element = 1
4. 3 % 3 = 0 = Array Element = 7

And again ...

​

function multiplyWeightFact(input) {

  const weighting = [7, 3, 1]


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

    input[index] *= weighting[index % weighting.length];


  }
  return input;
}
let input = [5,4,3,2,1]

console.log(multiplyWeightFact(input));

​

Answer 3

您可以只对输入进行map操作，然后根据其索引将其乘以权重。然后，我们可以使用remainder operator将索引保持在权重数组的范围内。

​

function multiplyWeightFact(input, weight){  
  return input.map((num, index) => num * weight[index % weight.length]);
}

const weight = [7, 3, 0];
const input = [24, 3, 0, 56, 43, 34];

const result = multiplyWeightFact(input, weight);

console.log(result);

​