Question

我有一个字符串列表，例如：

{ abc001, abc002, abc003, cdef001, cdef002, cdef004, ghi002, ghi001 }

我想获得所有常见的唯一前缀;例如，对于上面的列表：

{ abc, cdef, ghi }

我该怎么做？

Answer 1

var list = new List<String> {
    "abc001", "abc002", "abc003", "cdef001",
    "cdef002", "cdef004", "ghi002", "ghi001"
};
var prefixes = list.Select(x = >Regex.Match(x, @"^[^\d]+").Value).Distinct();

Answer 2

您可以使用正则表达式选择文本部分，然后使用HashSet<string>添加该文本部分，以便不添加重复项：

using System.Text.RegularExpressions;


//simulate your real list 
List<string> myList = new List<string>(new string[] { "abc001", "abc002", "cdef001" });   

string pattern = @"^(\D*)\d+$";
//  \D* any non digit characters, and \d+ means followed by at least one digit,
// Note if you want also to capture string like "abc" alone without followed by numbers
// then the pattern will be "^(\D*)$"

Regex regex = new Regex(pattern);

HashSet<string> matchesStrings = new HashSet<string>();

foreach (string item in myList)
{
    var match = regex.Match(item);

    if (match.Groups.Count > 1)
    {
        matchesString.Add(match.Groups[1].Value);
    }
}

结果：

abc, cde

Answer 3

编写辅助类来表示数据可能是个好主意。例如：

public class PrefixedNumber
{
    private static Regex parser = new Regex(@"^(\p{L}+)(\d+)$");

    public PrefixedNumber(string source) // you may want a static Parse method.
    {
        Match parsed = parser.Match(source); // think about an error here when it doesn't match
        Prefix = parsed.Groups[1].Value;
        Index = parsed.Groups[2].Value;
    }

    public string Prefix { get; set; }
    public string Index { get; set; }
}

你需要提出一个更好的名字，当然还有更好的访问修饰符。

现在任务非常简单：

List<string> data = new List<string> { "abc001", "abc002", "abc003", "cdef001",
                                       "cdef002", "cdef004", "ghi002", "ghi001" };
var groups = data.Select(str => new PrefixedNumber(str))
                 .GroupBy(prefixed => prefixed.Prefix);

结果是所有数据，解析并按前缀分组。

Answer 4

假设您的前缀是所有字母字符并由第一个非字母字符终止，您可以使用以下LINQ表达式

List<string> listOfStrings = new List<String>() 
  { "abc001d", "abc002", "abc003", "cdef001", "cdef002", "cdef004", "ghi002", "ghi001" }; 

var prefixes = (from s in listOfStrings
                select new string(s.TakeWhile(c => char.IsLetter(c)).ToArray())).Distinct();

从字符串列表中提取公共前缀

4 个答案: