[英]Ramda - Transform array by multiple groupings
我正在嘗試使用ramda
完成以下操作:
這是array
的外觀示例:
[
{
id: 1,
value: "ON",
type: "TYPE_1"
},
{
id: 1,
value: "OFF",
type: "TYPE_1"
},
{
id: 2,
value: "ON",
type: "TYPE_1"
}, {
id: 3,
value: "OFF",
type: "TYPE_2"
},
{
id: 3,
value: "OFF",
type: "TYPE_2"
},
{
id: 3,
value: "OFF",
type: "TYPE_2"
}
]
這是我希望它的外觀:
[
{
name: "TYPE_1"
enabled: 2,
disabled: 0,
},
{
name: "TYPE_2",
enabled: 0,
disabled: 1
}
]
基本上我需要按type
和id
分組,它們的組合可以重復但只占一個。
這是我已經嘗試過的:
pipe(
groupBy(prop('type')),
map(applySpec({
name: pipe(head, prop('type')),
enabled: reduce((acc, item) => item.value === "ON" ? add(acc, 1) : acc, 0),
disabled: reduce((acc, item) => item.value === "OFF" ? add(acc, 1) : acc, 0)
})),
values,
)(list)
但它不起作用,因為它返回以下內容:
[
{
name: "TYPE_1",
enabled: 2,
disabled: 1
},
{
type: "TYPE_2",
enabled: 0,
disabled: 3
]
缺少的部分是只考慮每種type
的每個id
。
您需要按id
再次分組,從每個子組中取出頭部,展平,然后應用規范:
const { pipe, groupBy, prop, values, map, applySpec, head, ifElse, any, always, filter, propEq, length } = R const fn = pipe( groupBy(prop('type')), values, map(pipe( groupBy(prop('id')), values, map(applySpec({ name: pipe(head, prop('type')), value: ifElse(any(propEq('value', 'ON')), always('ON'), always('OFF')), })), applySpec({ name: pipe(head, prop('name')), enabled: pipe(filter(propEq('value', 'ON')), length), disabled: pipe(filter(propEq('value', 'OFF')), length), }) )), ) const arr = [{"id":1,"value":"ON","type":"TYPE_1"},{"id":1,"value":"OFF","type":"TYPE_1"},{"id":2,"value":"ON","type":"TYPE_1"},{"id":3,"value":"OFF","type":"TYPE_2"},{"id":3,"value":"OFF","type":"TYPE_2"},{"id":3,"value":"OFF","type":"TYPE_2"}] const result = fn(arr) console.log(result)
<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.27.0/ramda.js"></script>
嘗試這個:
const transform = applySpec({
name: head,
enabled: pipe(last, filter(propEq('value', 'ON')), length),
disabled: pipe(last, filter(propEq('value', 'OFF')), length),
})
const fn = pipe(groupBy(prop('type')), toPairs, map(transform))
這是另一種方法,與 OriDrori 的方法有些不同。 它與給定的情況相匹配,但我仍然不確定一般規則,因此這可能實際上並沒有正確捕獲需求。
const extract = pipe ( groupBy (toString), // {JSON_key1: [{id, value, type}, {id, value, type}, ...] JSON_key2: [{id, value, type}, ...], ...} map (head), // {JSON_key1: {id, value, type}, JSON_key2: {id, value, type}, ...} values, // [{id, value, type}, {id, value, type}, ...] groupBy (prop ('type')), // {TYPE_1: [{id, value, type}, {id, value, type}, ...], "TYPE_2":[{id, value, type}]} map (countBy (prop ('value'))), // {TYPE_1: {ON: 2, OFF: 1}, TYPE_2: {OFF: 1}} toPairs, // [[TYPE_1, {ON: 2, OFF: 1}], [TYPE_2, {OFF: 1}]] map (applySpec ({ type: nth(0), enabled: pathOr(0, [1, 'ON']), disabled: pathOr(0, [1, 'OFF']) })) // [{type: "TYPE_1", enabled: 2, disabled: 1}, {type: "TYPE_2", enabled: 0, disabled: 1}] ) const data = [{id: 1, value: "ON", type: "TYPE_1"}, {id: 1, value: "OFF", type: "TYPE_1"}, {id: 2, value: "ON", type: "TYPE_1"}, {id: 3, value: "OFF", type: "TYPE_2"}, {id: 3, value: "OFF", type: "TYPE_2"}, {id: 3, value: "OFF", type: "TYPE_2"}]; console.log (extract (data))
<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.27.0/ramda.js"></script> <script> const {pipe, groupBy, toString, map, head, values, prop, countBy, toPairs, applySpec, nth, pathOr} = R </script>
Ramda 的toString
並不是特別快。 如果您願意,可以將管道的第一行替換為以下內容:
groupBy (({id, value, type}) => `${id}|${value}|${type}`),
此外, map(applySpec)
行感覺有點復雜。 我們可以用這樣的東西替換它們:
map (([type, {OFF: disabled = 0, ON: enabled = 0}]) => ({type, enabled, disabled}))
請注意小型、相對簡單的單個轉換管道的樣式。 這對我來說是 Ramda 的最佳選擇。 Ramda 旨在支持許多不同的 styles 函數式編程,但這種風格是最核心的。
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