如何比较node.js中的两个arrays

Question

我有两个 arrays。

let runArray = ['Welcome', 'Hello']

let data = [{
  Node:'Good',
  Session:'2',
  Run:'Welcome',
  Run_Group:'Display',
  Elapsed_Ms: '1000'
}]

我在data数组中有 2600 个对象，在runArray中有 50 个对象。 而且元素的数量可能更多。

重点是将runArray中的每个索引与data[index].Run属性进行比较，以便我可以计算Elapsed_Ms属性的平均值（来自数据）。

有什么选择吗？

Answer 1

再见，这里是一个工作示例：

 let runArray = ['Welcome', 'Hello']; let data = [{Node:'Good', Session:'2', Run:'Welcome', Run_Group:'Display', Elapsed_Ms: '1000'}, {Node:'Good', Session:'2', Run:'Welcome', Run_Group:'Display', Elapsed_Ms: '500'}, {Node:'Good', Session:'2', Run:'Hello', Run_Group:'Display', Elapsed_Ms: '1000'}]; let averages = []; runArray.map(el => { let filteredArray = data.filter(dat => dat.Run === el); let avg = filteredArray.reduce((a, b) => a + parseInt(b.Elapsed_Ms), 0)/filteredArray.length; let appo_obj = {index: el, average: avg}; averages.push(appo_obj); }) console.log(averages)

编辑：正如@MattJHoughton 所建议的，for 循环对性能更好。

 let runArray = ['Welcome', 'Hello']; let data = [{Node:'Good', Session:'2', Run:'Welcome', Run_Group:'Display', Elapsed_Ms: '1000'}, {Node:'Good', Session:'2', Run:'Welcome', Run_Group:'Display', Elapsed_Ms: '500'}, {Node:'Good', Session:'2', Run:'Hello', Run_Group:'Display', Elapsed_Ms: '1000'}]; let averages = []; for(let i=0; i<runArray.length;i++) { let filteredArray = data.filter(dat => dat.Run === runArray[i]); let avg = filteredArray.reduce((a, b) => a + parseInt(b.Elapsed_Ms), 0)/filteredArray.length; let appo_obj = {index: runArray[i], average: avg}; averages.push(appo_obj); } console.log(averages)

Answer 2

扩展您现有的代码，我们需要循环您的runArray的值以查找data数组中的任何匹配项目，保持总运行时间的运行总和和数据项计数。

 let runArray = ['Welcome', 'Hello']; let data = [{ Node:'Good', Session:'2', Run:'Welcome', Run_Group:'Display', Elapsed_Ms: '1000' }]; let sumElapsedMs = 0; let numberOfItems = 0; // loop over runArray runArray.forEach((value) => { // find the first matching entry in data array const matchedDataItem = data.find((dataItem) => { return dataItem.Run === value; }); // sum total elapsed & number of data entries if (matchedDataItem) { numberOfItems++; sumElapsedMs += matchedDataItem.Elapsed_Ms; } }); // calculate average (else default: undefined) const averageElapsedMs = numberOfItems? sumElapsedMs/numberOfItems: undefined; console.log('Average Elapsed (mS)', averageElapsedMs);