如何按指定数组顺序分组嵌套数组元素并合并对应值？

Hey there! Let's work through this problem step by step—we need to group the nested arrays by the exact order defined in ind, then merge their corresponding numeric values column-wise. Here's how to make it happen:

Step 1: Lay Out the Original Data #

First, let's recap your input arrays for clarity:

const ind = ["Apple", "Pear", "Banana"];
const arr = [ 
  [ "Pear", 12, 34, 54, 76, 23, 232 ], 
  [ "Apple", 54, 22, 11, 23, 21, 33 ], 
  [ "Banana", 54, 65, 11, 43, 66, 75 ], 
  [ "Pear", 23, 11, 46, 76, 33, 98 ], 
  [ "Apple", 12, 34, 54, 76, 23, 232 ], 
  [ "Banana", 54, 22, 11, 23, 21, 33 ], 
];

Step 2: Implement the Solution Code #

Here's the code that will transform your input into the desired output:

// 1. First, group all value arrays by their fruit name
const fruitGroups = arr.reduce((acc, currentItem) => {
  const fruitName = currentItem[0];
  const numericValues = currentItem.slice(1); // Grab all values after the fruit name
  
  if (!acc[fruitName]) {
    acc[fruitName] = [];
  }
  acc[fruitName].push(numericValues);
  return acc;
}, {});

// 2. Build the final result following the order in `ind`
const finalResult = ind.map(fruit => {
  const allValueArrays = fruitGroups[fruit];
  // Merge values column-wise: collect the nth value from each array
  const mergedColumns = allValueArrays[0].map((_, index) => {
    return allValueArrays.map(valueArr => valueArr[index]);
  });
  
  // Combine fruit name with merged columns
  return [fruit, ...mergedColumns];
});

console.log(finalResult);

Step 3: Check the Output #

When you run this code, you'll get exactly the structure you want (note: I spotted a small typo in your expected result for Pear's last value—it should be [232, 98] instead of [232, 38], since the original Pear subarrays end with 232 and 98):

[
  ["Apple", [54,12], [22,34], [11,54], [23,76], [21,23], [33,232]],
  ["Pear", [12,23], [34,11], [54,46], [76,76], [23,33], [232,98]],
  ["Banana", [54,54], [65,22], [11,11], [43,23], [66,21], [75,33]]
]

Quick Breakdown of How It Works #

• Grouping with reduce: We loop through arr and build an object where each key is a fruit name, and the value is an array of all numeric value lists for that fruit. This makes it easy to fetch all values for a specific fruit later.
• Mapping with ind: We iterate over the ind array to guarantee our final result follows the exact order you specified. For each fruit, we use map to create merged columns—for every index position, we pull the value from each of the fruit's value arrays and combine them into a subarray.
• Assembling the Result: We attach the merged column subarrays to the fruit name to form each entry in our final array.

内容的提问来源于stack exchange，提问作者leyar.themes