如何使用 Ramda 按一个键分组并总结其他键? [英] How to group by a key and sum other keys with Ramda?

问题描述

假设我有一个这样的对象数组:

<预><代码>[{'prop_1':'key_1'，'prop_2':23，'prop_3':45}，{'prop_1':'key_1'，'prop_2':56，'prop_3':10}，{'prop_1':'key_2'，'prop_2':10，'prop_3':5}，{'prop_1':'key_2'，'prop_2':6，'prop_3':7}]

我想按第一个属性分组并对其他属性的值求和，得到这样的数组:

<预><代码>[{'prop_1':'key_1'，'prop_2':79，'prop_3':55}，{'prop_1':'key_2'，'prop_2':16，'prop_3':12}]

使用 Ramda 执行此操作的正确方法是什么?我尝试使用以下内容:

R.pipe(R.groupBy(R.prop('prop_1')),R值，R.reduce(R.mergeWith(R.add), {}))

但这也是'prop_1'的值的总和.

解决方案

您需要映射组，然后缩小每个组.检查当前合并键的值.如果值为数字，则添加值.如果不只是返回第一个值:

const { pipe, groupBy, prop, values, map, reduce, mergeWith, ifElse, is, add, identity } = Rconst fn = 管道(groupBy(prop('prop_1')),价值观，地图(减少(mergeWith(ifElse(is(Number), add, identity)),{})))const data = [{"prop_1":"key_1","prop_2":23,"prop_3":45},{"prop_1":"key_1","prop_2":56,"prop_3":10},{"prop_1":"key_2","prop_2":10,"prop_3":5},{"prop_1":"key_2","prop_2":6,"prop_3":7}]const 结果 = fn(data)console.log(result)

<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.27.0/ramda.js"></script>

Suppose I have an array of objects like this:

[
{'prop_1': 'key_1', 'prop_2': 23, 'prop_3': 45},
{'prop_1': 'key_1', 'prop_2': 56, 'prop_3': 10},
{'prop_1': 'key_2', 'prop_2': 10, 'prop_3': 5},
{'prop_1': 'key_2', 'prop_2': 6, 'prop_3': 7}
]

I would like to group by the first property and sum the values of the other properties, resulting in an array like this:

[
{'prop_1': 'key_1', 'prop_2': 79, 'prop_3': 55},
{'prop_1': 'key_2', 'prop_2': 16, 'prop_3': 12}
]

What is the correct way to do this using Ramda? I have attempted to use the following:

R.pipe(
R.groupBy(R.prop('prop_1')),
R.values,
R.reduce(R.mergeWith(R.add), {})
)

But this sums also the value of 'prop_1'.

解决方案

You'll need to map the groups, and then reduce each group. Check the values of the currently merged keys. If the value is a Number add the values. If not just return the 1st value:

const { pipe, groupBy, prop, values, map, reduce, mergeWith, ifElse, is, add, identity } = R

const fn = pipe(
  groupBy(prop('prop_1')),
  values,
  map(reduce(
    mergeWith(ifElse(is(Number), add, identity)),
    {}
  ))
)

const data = [{"prop_1":"key_1","prop_2":23,"prop_3":45},{"prop_1":"key_1","prop_2":56,"prop_3":10},{"prop_1":"key_2","prop_2":10,"prop_3":5},{"prop_1":"key_2","prop_2":6,"prop_3":7}]

const result = fn(data)

console.log(result)

<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.27.0/ramda.js"></script>

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