从文本文件解析字符串并使用LINQ

Question

I have a textfile which stores on each line a list of int arrays of the size 2. Each array is seperated by ';' and the int are seperated by ',' . The ints represent coordinates. For example what you may see on a line is

1,0;5,9;3,2;6,7

of which the array of coordinates would be [1,0], [5,9], [3,2], [6,7] (int[2]). This would be put inside a list [[1,0], [5,9], [3,2], [6,7]] . Then this list would be added to another list [[[1,0], [5,9], [3,2], [6,7]], [[a,b], [c,d], [e,f], [g,h]], [[i,j], [k,l], [m,n], [o,p]]] (Sorry if the representation is a bit dodgy). What I would like help with is parsing

1,0;5,9;3,2;6,7

to add to a list which is List<List<int[]>> so a data structure which stores n amount of sets of n amount of integer coordinates. I have gathered I need to use parsing and possibly LINQ.

public class FileHandler : MonoBehaviour {

    string tileDataFile = "TileData.txt";
    List<List<int[]>> tileData = new List<List<int[]>>;
    bool FileExists()
    {
        if (File.Exists(tileDataFile))
        {
            return true;
        }
        else
        {
            return false;
        }
    }

    void GetFileData()
    {
        if (FileExists())
        {
            StreamReader SR = new StreamReader(tileDataFile, Encoding.Default);
            using (SR)
            {
                do
                {
                    tileData.Add(SR.ReadLine().Split(';').Where())                    
                }
            }
        }
    }

}

I have had a bit of experience using LINQ but I am not competent to a level where I can tackle this. Can anyone suggest a solution? I hope I explained well enough.

Answer 1

Just apply the split until you brake the line to something that can be used to build a List of int arrays.

var result = new List<int[]>();
foreach(var line in lines)
{
   var itemsForArray = line.Split(';');
   foreach(var intItems in itemsForArray)
   {
      var intItemsSplitted = intItems.Split(',');
      var firstValue = int.Parse(intItemsSplitted[0]);
      var secondValue = int.Parse(intItemsSplitted[1]);

      result.Add(new int[]{firstValue, secondValue});
   }
}

The LINQ approach (query):

var text = "1,2;2,2;1,4;0,1";
var result = (from t in text.Split(';')
              let s = t.Split(',')
              select new int[]    
              { 
                  int.Parse(s[0]),    
                  int.Parse(s[1]) 
              }).ToList();

If you prefer method syntax:

var result = text.Split(';')
    .Select(i => new int[]
    {
        int.Parse(i.Split(',')[0]),
        int.Parse(i.Split(',')[1])
    }).ToList();

I did not perform any checks, so they should be inserted there for code to be safe

Answer 2

ok since you have full control of data format, then it is easier to serialize/deserialize your List> directly without the need to parse it yourself, you have several serialization options, there Newton.Json and you can serialize it to Json text, another option is to serialize it to Binary using BinaryFormatter .NET class and last you can use .NET XMLSerializer.

usage for all of them is straight forward, as an example, if you chose Newton Json converter, you download Nuget package and then call it like this:

string serializedObject = JsonConvert.SerializeObject(YourList);

then you save this string to a text file.

now to retrieve it, you do something like this,read the textfile that has the serialized list and place it in a string then:

 List<List<int[]>> myList= JsonConvert.DeserializeObject<List<List<int[]>>(serializedObject);

if you decide to use binary, here is MSDN article:

https://msdn.microsoft.com/en-us/library/system.runtime.serialization.formatters.binary.binaryformatter(v=vs.110).aspx

Answer 3

I assume the performance of this will not be all that great, and to be honest I would normally prefer to use json to do this, but here is a one liner linq that does what you want. Also absolutely no safety if one of the values is not an integer.

var line = "1,0;5,9;3,2;6,7";
            var list = line.Split(';').Select(a => a.Split(',').Select(b => int.Parse(b)).ToArray());
            foreach(var item in list){
                Console.WriteLine("a:" + item[0] + ", b:" + item[1]);
            }

Answer 4

If you want to do it in one expression, you could use this:

Regex.Split( input, Regex.Escape( Environment.NewLine ) )
.Select( x => 
    x.Split( ';' ).Select( y =>
        y.Split( ',' )
        .Select( Int32.Parse )
        .ToList() )
    .ToList() )
.ToList();