如何在Javascript中检查数组类型是否为累积和类型

Question

正如我在标题中提到的，我有多个包含一些数据的数组。一些数组具有累积数字，其他数组具有随机数据。我想做的是，
逻辑：if an array is not cumulative, then make it cumulative.

//Randomized arrays are
arrays= [[
  '0.029', '0.029', '0.030', '0.030', '0.031', '0.031',
  '0.032', '0.032', '0.033', '0.034', '0.034', '0.034',
  '0.039', '0.039', '0.001',
  '0.001', '0.002', '0.003', '0.003', '0.004', '0.004',
  '0.005', '0.006', '0.006', '0.007', '0.007', '0.008',
  '0.011', '0.012', '0.012', '0.013', '0.014', '0.014',
  '0.015', '0.015', '0.016', '0.017'
],
[
  '0.002', '0.002', '0.002', '0.002',
  '0.003', '0.003', '0.003', '0.003',
  '0.003', '0.004', '0.004', '0.004',
  '0.000', '0.000', '0.000', '0.001',
  '0.001', '0.001', '0.001', '0.001',
  '0.001', '0.001', '0.001', '0.002',
  '0.002', '0.002', '0.002', '0.002',
  '0.003', '0.003', '0.003'
],
// Cumulative array
[
  '0.002', '0.004', '0.006', '0.008',
  '0.011', '0.014', '0.017', '0.020',
  '0.023', '0.027', '0.031', '0.035',
  '0.035', '0.035', '0.035', '0.036',
  '0.037', '0.038', '0.039', '0.040',
  '0.041', '0.042', '0.043', '0.045',
  '0.047', '0.049', '0.051', '0.053',
  '0.055', '0.057', '0.059', '0.061',
  '0.064', '0.067', '0.070'
]]

我试过这样。

var lastData=[]
for (i in arrays) {
// I thought that if array still includes 0 data inside, than make it cumulative
   if (arrays[i].indexOf("0.000") !== -1) {
       console.log(i, ' is cumulative'
       lastData = arrays[i].map((elem, index) =>
                  arrays[i].slice(0, index + 1)
                           .reduce((a, b) => 
                            (parseFloat(a) + parseFloat(b)).toFixed(3)))
   }
}

Answer 1

您可以使用Array.map() 和自定义函数isCumulative 来确定每个数组是否连续增加。

在本例中，我们将使用Array.every() 来确保每个数字都在增加：

arrays= [[
  '0.029', '0.029', '0.030', '0.030', '0.031', '0.031',
  '0.032', '0.032', '0.033', '0.034', '0.034', '0.034',
  '0.039', '0.039', '0.001',
  '0.001', '0.002', '0.003', '0.003', '0.004', '0.004',
  '0.005', '0.006', '0.006', '0.007', '0.007', '0.008',
  '0.011', '0.012', '0.012', '0.013', '0.014', '0.014',
  '0.015', '0.015', '0.016', '0.017'
],
[
  '0.002', '0.002', '0.002', '0.002',
  '0.003', '0.003', '0.003', '0.003',
  '0.003', '0.004', '0.004', '0.004',
  '0.000', '0.000', '0.000', '0.001',
  '0.001', '0.001', '0.001', '0.001',
  '0.001', '0.001', '0.001', '0.002',
  '0.002', '0.002', '0.002', '0.002',
  '0.003', '0.003', '0.003'
],
// Cumulative array
[
  '0.002', '0.004', '0.006', '0.008',
  '0.011', '0.014', '0.017', '0.020',
  '0.023', '0.027', '0.031', '0.035',
  '0.035', '0.035', '0.035', '0.036',
  '0.037', '0.038', '0.039', '0.040',
  '0.041', '0.042', '0.043', '0.045',
  '0.047', '0.049', '0.051', '0.053',
  '0.055', '0.057', '0.059', '0.061',
  '0.064', '0.067', '0.070'
],
[
   '0.000','0.001','0.002','0.003' 
],
[
   '0.000','0.002','0.001','0.003' 
]
]

// Return true if elements in the array are monotonically increasing _or_ equal to previous element.
function isCumulative(arr) {
    return arr.every(greaterThanOrEqual);
}

function greaterThanOrEqual(el, idx, arr) {
    const prevElement = arr[idx-1];
    return !idx || +el >= +prevElement;
}

const result = arrays.map(isCumulative);
console.log('Result:', result)

对于单个数组：

function greaterThanOrEqual(el, idx, arr) {
    const prevElement = arr[idx-1];
    return !idx || +el >= +prevElement;
}

const singleArray = ['0.01', '0.02', '0.03'];
const result = singleArray.every(greaterThanOrEqual);
console.log('singleArray result:', result)