Angular-如何使用求和和分组 [英] Angular - How to use sum and group by

问题描述

我需要根据ID对记录进行分组并显示重量的总和.有人可以让我知道Angular中的总和和分组方法吗?

I need to group the records based on ID and display sum of weight. can someone please let me know the sum and group by method in Angular.

API响应:

data = [
  {Id:1, name: 'ABC', weight: 10 },
  {Id:1, name: 'ABC', weight: 14 },
  {Id:1, name: 'ABC', weight: 16 },
  {Id:2, name: 'DEF', weight: 23 },
  {Id:2, name: 'DEF', weight: 22 },
  {Id:4, name: 'GHI', weight: 44 },
  {Id:4, name: 'GHI', weight: 41 }
]

预期输出:

dataResult =  [
      {Id:1, name: 'ABC', weight: 40 },
      {Id:2, name: 'DEF', weight: 45 },
      {Id:4, name: 'GHI', weight: 85 }
    ]

推荐答案

您可以使用 Array.reduce()进行迭代，并使用 Array.find()查找按ID的项.然后，您可以按以下方式计算总和:

You can use Array.reduce() to iterate over and Array.find() to find item by id. Then you can calculate the sum as followings:

const data = [
  {Id:1, name: 'ABC', weight: 10 },
  {Id:1, name: 'ABC', weight: 14 },
  {Id:1, name: 'ABC', weight: 16 },
  {Id:2, name: 'DEF', weight: 23 },
  {Id:2, name: 'DEF', weight: 22 },
  {Id:4, name: 'GHI', weight: 44 },
  {Id:4, name: 'GHI', weight: 41 }
]

const calculated = data.reduce((acc, item) => {
  
  let accItem = acc.find(ai => ai.Id === item.Id)
  
  if(accItem){
      accItem.weight += item.weight 
  }else{
     acc.push(item)
  }

  return acc;
},[])

console.log(calculated)

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