Question

我有这个问题。有一个字符串

string [5] names = { "John", "Sam", "Harry", "Sam", "John" }

我需要找到数组中最常见的元素。我尝试使用：

string MostCommon = names.GroupBy(v => v)
    .OrderByDescending(g => g.Count())
    .First()
    .Key;

不幸的是，它只找到一个元素，即MostCommon = John，在这种情况下，我不仅需要John，还需要Sam。我怎么能这样做？在这种情况下，LINQ不是必需的吗？

Answer 1

First显然只会选择序列的第一个元素。但是，您需要具有相同编号的所有组。因此，请选择每个组的名称和编号，然后再订购。最后选择与第一组具有相同计数的所有组。

var groups = names.GroupBy(x => x)
    .Select(x => new { x.Key, Count = x.Count() })
    .OrderByDescending(x => x.Count);
int max = groups.First().Count;
var mostCommons = groups.Where(x => x.Count == max);

编辑：您还可以在最后一个语句中使用TakeWhile而不是Where，以避免对groups - 列表中的最后一个元素进行不必要的比较，并在第一个组时立即停止发现元素少于第一个元素：

var mostCommons = groups.TakeWhile(x => x.Count == groups.First().Count);

Answer 2

这可以按照以下方式完成 -

import { Component, OnInit } from '@angular/core';
import { Http } from '@angular/http';

@Component({
  selector: 'app-book-list',
  templateUrl: './book-list.component.html',
  styleUrls: ['./book-list.component.css']
})
export class BookListComponent implements OnInit {
  books: any;

  constructor(private http: Http) { }

  ngOnInit() {
    this.http.get('/api/books.json')
      .subscribe(response => this.books = response.json());
  }

}

Answer 3

根据您找到的最常见名称的数量，将您的第一个LINQ与另一个类似的linq结合起来。

string MostCommon = names.GroupBy(v => v)
    .OrderByDescending(g => g.Count())
    .First();

int count = names.Where(x => x == MostCommon).Count();

var mostCommonList = names.GroupBy(v => v)
    .Where(g => g.Count() == count);

Answer 4

//With Dictionary
//This is more useful if you are looking to interview big companies otherwise use the 
 Linq option which is short and handy

public static int MaxOccurrenceOfWord(string[] words)
    {
        var counts = new Dictionary<string, int>();
        int occurrences = 0;
        foreach (var word in words)
        {
            int count;
            counts.TryGetValue(word, out count);
            count++;
             //Automatically replaces the entry if it exists;
            //no need to use 'Contains'
            counts[word] = count;
        }

        string mostCommonWord = null;
        foreach (var pair in counts)
        {
            if (pair.Value > occurrences)
            {
                occurrences = pair.Value;
                mostCommonWord = pair.Key;
            }
        }
        Console.WriteLine("The most common number is {0} and it appears {1} times",
            mostCommonWord, occurrences);

        return occurrences;

    }

C＃查找字符串数组中最常见的字符串

4 个答案: