如何通过任何字符串项的前 3 个字符对字符串类型数组项进行分组和收集？

Question

提供了一个单词数组，其中一些单词很可能有它们的前 3 个字符（考虑不区分大小写）...类似于此单词列表示例...

['Bob', 'Bobby', 'Robert', 'Robby']

因为 'Bob' 和 'Bobby' 以及 'Robert' 和 'Robby' 分别有共同点 'Bob' 'Rob'，我寻找一种方法，该方法将 return 两个分组单词数组的数组，对于前一个示例是 ...

[['Bob', 'Bobby'], ['Robert', 'Robby']]

这样的方法会是什么样子？

Answer 1

将名称收集到一个对象中，以它们的开头作为键（参见 String.substring), and then get the values of this object (see Object.values()）

function getArraysByNameFirstThreeChars(names) {  
  // declare the object for collecting similarely beginning names
  const resultObject = {};

  // iterate through the names
  for (const name of names) {
    // get 3 first characters of the name
    const strStart = name.substring(0, name.length >= 3 ? 3 : name.length);
    // if there's already a member in the object
    // for this beginning, push the name to it
    if (resultObject[strStart]) {
      resultObject[strStart].push(name);
    } else {
      // otherwise, create a member in the collection object
      // for this name-beginning, comprising of an array
      // with only current name in it
      resultObject[strStart] = [name];
    }
  }
  return Object.values(resultObject);
}

const names = ['Bob', 'Bobby', 'Robert', 'Robby'];
const whatYouWant = getArraysByNameFirstThreeChars(names);

console.log(whatYouWant);

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Answer 2

经常 Array.prototype.reduce 证明自己是 瑞士军刀。

一个可配置的减速器函数就可以完成这项工作。另一个要提供的起始值，即收集器对象，确实具有 groups 对象，该对象后来保存所有收集和分组的单词列表。也可以配置 length 属性。它表示任何单词的起始序列的字符数，所有单词将根据该字符数进行分组和收集。省略此属性在内部默认为 3.

的数值

reducer 专门收集唯一词。因此将过滤待处理数组中的重复项。

对于预期为单词数组的数组的最终结果，只需将 return 值的 groups 键传递给 Object.values ...

// Added clarification.
// In this case they share the first 3 letters, bob and rob.

function groupAndCollectWordsBySimilarStartSequences(collector, word) {
  const { groups, length = 3 } = collector;
  const index = collector.index || (collector.index = {});

  // process non duplicate words of minimum length only.
  if ((word.length >= length) && !(word in index)) {

    const groupKey = word.slice(0, length).toLowerCase();
    const groupList = groups[groupKey] || (groups[groupKey] = []);

    groupList.push(word);
    index[word] = word;
  }
  return collector;
}

console.log(
  'grouped index :',

  ['Bob', 'Bobby', 'Robert', 'Robby', 'Bob', 'Robby'].reduce(
    groupAndCollectWordsBySimilarStartSequences, {
      groups: {},
      length: 2,
    }
  ).groups
);
console.log(
  'array of arrays :',

  Object.values(['Bob', 'Bobby', 'Robert', 'Robby'].reduce(
    groupAndCollectWordsBySimilarStartSequences, {
      groups: {},
      length: 2,
    }
  ).groups)
);
console.log('\n');

console.log(
  'grouped index :',

  ['Bob', 'Bobby', 'Robert', 'Robby', 'Bob', 'Robby'].reduce(
    groupAndCollectWordsBySimilarStartSequences, {
      groups: {},
    }
  ).groups
);
console.log(
  'array of arrays :',

  Object.values(['Bob', 'Bobby', 'Robert', 'Robby'].reduce(
    groupAndCollectWordsBySimilarStartSequences, {
      groups: {},
    }
  ).groups)
);
console.log('\n');

console.log(
  'grouped index :',

  ['Bob', 'Bobby', 'Robert', 'Robby', 'Bob', 'Robby'].reduce(
    groupAndCollectWordsBySimilarStartSequences, {
      groups: {},
      length: 4,
    }
  ).groups
);
console.log(
  'array of arrays :',

  Object.values(['Bob', 'Bobby', 'Robert', 'Robby'].reduce(
    groupAndCollectWordsBySimilarStartSequences, {
      groups: {},
      length: 4,
    }
  ).groups)
);
console.log('\n');

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如何通过任何字符串项的前 3 个字符对字符串类型数组项进行分组和收集？

How does one group and collect string-type array-items by any string-item's first 3 characters?

javascript

arrays

algorithm

reduce

grouping