Removing Columns From A Pipe Delimited File C#

Question

I have a pipe delimited file with the following columns

Col0|Col1|Col2|Col3|Col4|Col5|Col6
data|data|data|data|data|data|data
data|data|data|data|data|data|data
data|data|data|data|data|data|data
data|data|data|data|data|data|data

I want to remove columns from a pipe delimited file.

        //THIS code will remove Col2
        string[] csvLines = File.ReadAllLines(@"Input.txt");


        string header = csvLines.FirstOrDefault(l => !String.IsNullOrWhiteSpace(l));
        if (header != null)
        {

                IEnumerable<string> allButWantedCols=null;

                allButWantedCols = csvLines
                       .Select(l => new { Columns = l.Split(new[] { '|' }, StringSplitOptions.None) })
                       .Where(x => x.Columns.Length > 2)
                       .Select(x => string.Join("|", x.Columns
                       .Where((col, index) => index != 2)
                       .Select(col => col.Trim())));

                // rewrite the file with all columns but balance:
                File.WriteAllLines(@"pipe_OUTPUT_.txt", allButWantedCols);

        }

The code above removes "Col2" and all of its data.

I am struggling to figure out how to remove multiple columns?

ie remove columns Col2,Col3,Col6

Answer 1

This is your current code:

allButWantedCols = csvLines
                       .Select(l => new { Columns = l.Split(new[] { '|' }, StringSplitOptions.None) })
                       .Where(x => x.Columns.Length > 2)
                       .Select(x => string.Join("|", x.Columns
                       .Where((col, index) => index != 2)
                       .Select(col => col.Trim())));

Change it to something along the lines of the below.

allButWantedCols = csvLines
                       .Select(l => new { Columns = l.Split(new[] { '|' }, StringSplitOptions.None) })
                       .Where(x => x.Columns.Length > 2)
                       .Select(x => string.Join("|", x.Columns
                       .Where((col, index) => index != 2 && index != 3 && index != 6)
                       .Select(col => col.Trim())));

You will potentially want to ensure that columns exist at said indexes first, but that should provide you what you've asked about in your initial question.