Read Csv using LINQ

Question

I am having a csv file like this

A, 22, 23, 12
B, 32, 4, 33
C, 34, 3 ,33

I want to print the sum and average of each row and skip the first column. How to do in LINQ using Lambda

Answer 1

var stuff = from l in File.ReadAllLines(filename)
            let x = l.Split(new [] {',', ' '}, StringSplitOptions.RemoveEmptyEntries)
                     .Skip(1)
                     .Select(s => int.Parse(s))
            select new
            {
                Sum = x.Sum(),
                Average = x.Average()
            };

If you're reading big files and memory use is a concern, then the following will work better using .NET 4:

var stuff = from l in File.ReadLines(filename)
            let x = l.Split(new [] {',', ' '}, StringSplitOptions.RemoveEmptyEntries)
                     .Skip(1)
                     .Select(s => int.Parse(s))
            select new
            {
                Sum = x.Sum(),
                Average = x.Average()
            };

In both cases, the stuff variable contains an enumerable which won't actually be executed until you start reading from it (e.g. inside a foreach loop).

Answer 2

        string csvFile = @"myfile.csv";
        string[] lines = File.ReadAllLines(csvFile);

        var values = lines.Select(l => new { FirstColumn = l.Split(',').First(), Values = l.Split(',').Skip(1).Select(v => int.Parse(v)) });
        foreach (var value in values)
        {
            Console.WriteLine(string.Format("Column '{0}', Sum: {1}, Average {2}", value.FirstColumn, value.Values.Sum(), value.Values.Average()));
        }

Answer 3

Try to use this old but still good library: FileHelpers Library

It's very easy to use:

char delimiter = ',';
var dt = FileHelpers.CsvEngine.CsvToDataTable(fileName,delimiter);

then just do:

var rowStats = dt.AsEnumerable()
                 .Select(x => x.ItemArray.Select(y => Convert.ToInt32(y)))
                 .Select(x => new { avg = x.Average(), sum = x.Sum() });

foreach (var rowStat in rowStats)
{
    Console.WriteLine("Sum: {0}, Avg: {1}", rowStat.sum, rowStat.avg);
}

Answer 4

string[] csvlines = File.ReadAllLines(@txtCSVFile.Text);

var query = from csvline in csvlines
  let data = csvline.Split(',')
  select new
  {
   ID = data[0],
   FirstNumber = data[1],
   SecondNumber = data[2],
   ThirdNumber = data[3]
  };

Answer 5

I just have discovered LinqToCsv library, it do all the parsing stuff and then you can query objects like collections and it supports deferred reading:

http://www.codeproject.com/Articles/25133/LINQ-to-CSV-library