Converting string array to double array

Question

I have a file with alot of numbers, each index has 4 subnumbers

no1 no2 no3 no4 
no1 no2 no3 no4 
no1 no2 no3 no4

The file is a cvs file, but I need to read the numbers into an array as type double and make an interpolating, so I need to walkthrough the table.

Until now I have this, but I am stuck and do not really know how I nicely can convert the file to double values, so I can start calculate on them. Any suggestion ?

var filelines = from line in file.Skip(5)
                select line.Split(';');

Can you show us an example of your input and the desired output? — LukeH
– LukeH, Commented Feb 10, 2015 at 11:26
why are you using Skip(5) ? if you are trying to skip header shouldn't it be Skip(1) ? — Selman Genç
– Selman Genç, Commented Feb 10, 2015 at 11:28
Do you need to retain the "lines", so one double[] per line or one double[] overall? — Tim Schmelter
– Tim Schmelter, Commented Feb 10, 2015 at 11:29
@Selman22: sometimes the first lines contain not only the header but also file informations or summaries. — Tim Schmelter
– Tim Schmelter, Commented Feb 10, 2015 at 11:30

Tim Schmelter · Accepted Answer · 2015-02-10 11:35:54Z

1

If you want a double[][], so one array per line:

double d;
double[][] lineValues = file.Skip(5)
    .Select(l => l.Split(new[]{';'}, StringSplitOptions.RemoveEmptyEntries))
    .Where(arr => arr.Length == 4 && arr.All(s => double.TryParse(s, out d)))
    .Select(arr => arr.Select(double.Parse).ToArray())
    .ToArray();

answered Feb 10, 2015 at 11:35

Tim Schmelter

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9 Comments

Jedhi Over a year ago

Thanks, linevalues is empty. I have tried to instantiate lineValues with lineValues = new lineValues(file.count), but does not Work. Do I miss something here ? And can I make it [][][][] so it is a Quattro array ?

Tim Schmelter Over a year ago

@Jedhi: what is a quattro array? Why do you need such thing? In above double[][] every line is transposed into a double[] so that you get one array for every line contains all fields' values. Why it doesn't seem to work? Maybe because your file has a different structure. I have added a strong validation rule: .Where(arr => arr.Length == 4 && arr.All(s => double.TryParse(s, out d))). Maybe the lines contain more than 4 fields or less or not all can be parsed to double.

Jedhi Over a year ago

Hi Tim. it Works when I delete the line .Where(arr => arr.Length == 4 && arr.All(s => double.TryParse(s, out d))). The file looks like # # # # # 10; 2,0; 0; 0 30; 4; 0; 0 50; 6; 0; 0 70; 8; 0; 0 Structure is always the same. Will it try to parse to double if there are 4 numbers ?

Tim Schmelter Over a year ago

@Jedhi: it is impossible to see the file structure in a comment. Please edit your question with sample lines in proper format(with line breaks and so on). It will only try to parse a line to a double[] if there are 4 numbers.

Tim Schmelter Over a year ago

@Jedhi: multidimensional arrays and LINQ don't play well together. You can have a look here: stackoverflow.com/questions/18896150/…

|

Selman Genç · Accepted Answer · 2015-02-10 11:27:24Z

1

You can split the line,parse each part into decimal and use SelectMany to flatten results:

file.Skip(5).SelectMany(line => line.Split(';').Select(decimal.Parse)).ToArray()

answered Feb 10, 2015 at 11:27

Selman Genç

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1 Comment

Jedhi Over a year ago

How can I make a Quattro array ? can i write double [][][][] = file.skip(5)... or any suggestion ?

Transcendent · Accepted Answer · 2015-02-10 12:03:37Z

If there is certain values in each row, like let's say your cvs data store has a specific number of fields, s wiser and strongly typed move is to first make up a model for your data store, which according to the information you provided would be:

public class MyCVSModel {
    public Double Number1 {get; set;} 
    public Double Number2 {get; set;} 
    public Double Number3 {get; set;} 
    public Double Number4 {get; set;} 
}

Now, you can:

public static IEnumerable<MyCVSModel> Converion(String FileName){
     var AllLines = System.IO.ReadAllLines(FileName);
     foreach(var i in AllLines){
        var Temp = i.Split('\t'); // Or any other delimiter
        if (Temp.Lenght >= 4){ // 4 is because you have 4 values in a row
           List<Double> TryConversion = new List<Double>();
           foreach(var x in Temp) {
              if (IsDouble(x))
                 TryConversion.Add(Convert.ToDouble(x));
              else
                 TryConversion.Add(0);
           }
           MyCVSModel Model = new MyCVSModel();
           Model.Number1 = TryConversion[0];
           Model.Number2 = TryConversion[1];
           Model.Number3 = TryConversion[2];
           Model.Number4 = TryConversion[3];
           yield return Model;
        }
     }
}

public static Boolean IsDouble(String Value) {
    Regex R = new Regex(@"^[0-9]*(?:\.[0-9]*)?$");
    return R.IsMatch(Value);
}

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