CODEWITHSUNDEEP
c#csv
user3170073
user3170073

Reputation: 193

Read CSV files to two arrays c#

I have a situation that need to make two arrays from each column of csv file. As shown below, the csv file contain two columns each column has a header titled 'period' and 'acceleration'. 

Period,Acceleration
0.01,0.6
0.05,0.82
0.1,1.26
0.15,1.403
0.2,1.383

I tried to use following code and then split this into two arrays. However, it did not break the numbers by comma. 

string[] allLines = File.ReadAllText(@"C:\ArsScale\Tars.csv").Split(',');

Upvotes: 0

Views: 2944

Answers (4)

James S
James S

Reputation: 3588

String.Split is not a robust way of parsing CSV fields, as they may contain commas within the fields etc

In any case you need to use File.ReadAllLines, not File.ReadAllText

File.ReadAllLines gives you a array of strings - 1 for each line.

You could then iterate through the array and copy to 2 other arrays for each item.

Example:

var lines = File.ReadAllLines (@"C:\ArsScale\Tars.csv");
var periods = lines.Skip(1).Select(x => x.Split(",")[0]).ToArray();
var accelerations = lines.Skip(1).Select(x => x.Split(",")[1]).ToArray();

However I'd advise a more robust method.

Have a look at this article: http://www.codeproject.com/Articles/415732/Reading-and-Writing-CSV-Files-in-Csharp

Upvotes: 0

Plue
Plue

Reputation: 1790

Use a StreamReader to read your csv line by line. Then split each line and add each value to a list. Finally create two arrays from your lists. 

List<Double> periodList = new List<Double>();
List<Double> accelerationList = new List<Double>();

StreamReader file = new System.IO.StreamReader(@"C:\ArsScale\Tars.csv");
string line = file.ReadLine();
while ((line = file.ReadLine()) != null)
{
    string[] data = line.Split(',');
    periodList.Add(Convert.ToDouble(data[0]);
    accelerationList.Add(Convert.ToDouble(data[1]);
}

Double[] periodArray = periodList.ToArray();
Double[] accelerationArray = accelerationList.ToArray();

Upvotes: 1

Exceptyon
Exceptyon

Reputation: 1582

static void getTwoArraysFromFile(string filein, ref double[] acc, ref double[] period)
{
    string line;

    List<double> p1 = new List<double>();
    List<double> p2 = new List<double>();

    System.IO.StreamReader file = new System.IO.StreamReader(filein);
    while ((line = file.ReadLine()) != null)
        try {
            String[] parms = line.Trim().Split(',');

            p1.Add(double.Parse(parms[1], CultureInfo.InvariantCulture));       
            p2.Add(double.Parse(parms[0], CultureInfo.InvariantCulture));
        }
        catch { }

    acc = p1.ToArray();
    period = p2.ToArray();
}

Upvotes: 4

Pete Garafano
Pete Garafano

Reputation: 4923

IEnumerable<string[]> allLines = File.ReadAllLines(@"C:\ArsScale\Tars.csv").Select(x => x.Split(','));

This will read all the lines from the text file, then split each line. The datatype will be IEnumerable of string[]. To change this to string[][], simply call .ToArray() after the Select statement.

This method is quick and simple, however it does absolutely no validation on the input. For example, the CSV spec allows for commas to be present inside of values as long as they are escaped. If you need to have validation of any kind, you need to look into a CSV parser, of which there are many.

If you need no validation, you're positive about the input, and don't care about good error handling, you can use the following:

var allLines = File.ReadAllLines(@"C:\ArsScale\Tars.csv").Select(x => x.Split(',').Select(y => double.Parse(y).ToArray())).ToArray();

This will give you double[][] as your output.

Upvotes: 2

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