transpose(object)?

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  • #158 來自 @Fil —— 已關閉，未合併

評估

難度
5/5
預估耗時
一週以上
新手友好度
20/100
Issue 類型
功能
描述清晰度
需要釐清
活躍度
停滯
技術堆疊
javascript
領域
data

研究方向

Read the existing transpose documentation in README.md and inspect the current d3.transpose implementation. The issue asks whether to overload it or introduce a separately named method, including behavior for both object-of-arrays and array-of-objects; settle the API and expected edge cases before implementation. Done means the chosen behavior is documented and covered by tests, but this issue gives no test file or decision on the API.

由索引模型根據 Issue 內容生成。

描述

We have transpose(matrix) which transposes the rows and columns of a matrix (an array of arrays). But you might want similar functionality to transpose an object whose values are arrays into an array whose elements are objects.

function transpose(object) {
  var m = 0;
  for (var k in object) m = Math.max(m, object[k].length);
  for (var i = -1, transpose = new Array(m); ++i < m;) {
    var o = transpose[i] = {};
    for (var k in object) {
      o[k] = object[k][i];
    }
  }
  return transpose;  
}

Where:

transpose({
  year: [2001, 2002],
  value: [1, 2]
})

Returns:

[
  {year: 2001, value: 1},
  {year: 2002, value: 2},
]

Should we try to overload d3.transpose to do both?

If so, how? The above implementation sort-of works for array-of-array input such as transpose([[0, 1, 2], [3, 4, 5]]), but returns an array of objects rather than an array of arrays. You could use Array.isArray to test whether the input is an Array and branch the behavior accordingly.

If not, what name should this new method have? transposeObject?

Also, if transpose(object) given an object whose values are arrays returns an array of objects, then transpose(array) given an array whose elements are objects should return an object whose values are arrays.

Maybe this is too magical.

主要語言
JavaScript
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465
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193
平均合併
5 小時 46 分鐘
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1

環境準備

這個專案沒有提供開發容器、Dockerfile 或貢獻指南，環境需要你自己搭建：先看它的 README，通用步驟見我們的新手貢獻指南。

從這裡開始

  1. 先讀完整個 Issue，再讀專案的貢獻指南。
  2. 在 Issue 下留言說明你要接手 —— 這能避免兩個人做同樣的事。
  3. Fork 儲存庫，在一個分支上完成修改。
  4. 送出 Pull Request，並在描述裡引用這個 Issue 編號。

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