如何使用 javascript 从对象数组中获取所需数据？

Question

我有这样的对象数组

var a = [
 {'time' : 1539664755070,'T-1': 23 },
 {'time' : 1539665095442,'H-1': 24 },
 {'time' : 1539666489560,'T-1': 42 },
 {'time' : 1539665095442,'H-1': 27 },
 {'time': 1539671682230,'H-1': 40.45,'T-2': 33},
 {'time': 1539671682230,'T-2': 30.45,'T-1': 65},
 {'time': 1539671682230,'T-2': 42.45,'H-1': 11},
 {'time': 1539671682230,'T-1': 50.45,'T-2': 85}
];

我想要这样的数据

data : {
  'T-1' : [23,42,50.45],
  'T-2' : [33,30.45,85],
  'H-1' : [24,27,40.45,11]
}

如何从给定数据中获取这些数据？

Answer 1

const data = a.reduce((acc, row) => {
  // Loop over keys of each row.
  Object.keys(row)
    // Filter out the "time" keys.
    .filter((key) => key !== 'time')
    // Collect the values by key, storing them in the accumulator.
    .forEach((key) => {
      if (typeof acc[key] === 'undefined') {
        acc[key] = []
      }

      acc[key].push(row[key])
    })

  return acc
}, {})

Answer 2

这是一个解决方案，如果有什么不明白的地方，请告诉我：

const result = {};

a.forEach(object => {
    // Loop on each entry in the original array
    Object.entries(object).forEach(([key,value]) => {
      // Loop through each entry of one entry of the original array 
      // (ex 'T-1', 'T-2')
      if(key !== 'time') {
        // It's a key that I'm interested in, so do logic
        if(!result[key]) {
          // If the key (example 'T-1') haven't been encountered yet, 
          // initialize it's entry in the result with an empty array
          result[key] = [];
        }
        result[key].push(value);
      }  
    });
});

Answer 3

您可以使用 array#reduce 和 Object.values() 来创建您的键的散列并添加与之对应的值。然后使用 Object.assign() 和 spread syntax 您可以创建最终对象。

let data = [ {'time' : 1539664755070,'T-1': 23 }, {'time' : 1539665095442,'H-1': 24 }, {'time' : 1539666489560,'T-1': 42 }, {'time' : 1539665095442,'H-1': 27 }, {'time': 1539671682230,'H-1': 40.45,'T-2': 33}, {'time': 1539671682230,'T-2': 30.45,'T-1': 65},{'time': 1539671682230,'T-2': 42.45,'H-1': 11}, {'time': 1539671682230,'T-1': 50.45,'T-2': 85} ],
  result = Object.assign({}, ...Object.values(data.reduce((r, o) => {
    let keys = Object.keys(o).filter(k => k !== 'time');
    keys.forEach(key => {
      r[key] = r[key] || {[key] : []};
      r[key][key].push(o[key]);
    });
    return r;
  },{})));
console.log(result);

Answer 4

使用 Map 而不是 Key,Value 数组的最佳用例。简化了很多事情。

如何使用 javascript 从对象数组中获取所需数据？

How can i get my required data from array of objects using javascript?

javascript

angular

angular5