How to create a .csv file from a Dictionary<List, List<string>> in C#

Question

I have a Dictionary(List, List(string)) (apologies, for some reason, this editor is not allowing me to type <>) which looks like the following:

Key: A --> Value:{1,2,3}
Key: B --> Value:{a,b,c}
Key: C --> Value:{Hi,Hello,Hola}

I would like to create a .csv file with Headers corresponding to my dictionary Keys, and 'Columns' corresponding to the List's.

So, for instance, First 'column in my csv file should be: column 'A', with values 1 2 3 Second 'column' in my csv file should be: column 'B', with values a b c, etc.. (Note that I would prefer that the ordering of the columns be kept, but it is ok if it's not)

Or in other words, since this will be a Comma Separated File, the First 'Row' (Headers) should be: A,B,C
2nd row: 1, a , Hi 3rd row: 2, b, Hello and 4th row: 3, c, Hola

What is the best way to achieve this in C#? I have tried researching this first, but most suggestions I seem to see online seem to not use a dictionary in the format Dictionary(List, List(string)).

I appreciate the help.

Answer 1

You can try this:

 static void Main(string[] args)
    {
        //Sample data declaration
        Dictionary<string, List<string>> data = new Dictionary<string, List<string>>();
        data.Add("Hello", new List<string>{"1", "2", "4"});
        data.Add("Foo", new List<string> { "3", "4", "7" });
        data.Add("World", new List<string> { "3", "4", "7" });

        DicToExcel(data, @"D:\my.csv");

    }

Here comes the logic:

    public static void DicToExcel(Dictionary<string, List<string>> dict, string path)
    {
            //We will put all results here in StringBuilder and just append everything
            StringBuilder sb = new StringBuilder();

            //The key will be our header
            String csv = String.Join(",",
                   dict.Select(d => d.Key));
            sb.Append(csv + Environment.NewLine);

            //We will take every string by element position
            String csv1 = String.Join(",",
                   dict.Select(d => string.Join(",", d.Value.First().Take(1))));
            sb.Append(csv1 + Environment.NewLine);

            String csv2 = String.Join(",",
                   dict.Select(d => string.Join(",", d.Value.Skip(1).Take(1))));
            sb.Append(csv2+ Environment.NewLine);

            String csv3 = String.Join(",",
                 dict.Select(d => string.Join(",", d.Value.Skip(2).Take(1))));
            sb.Append(csv3);

            //Write the file
            System.IO.File.WriteAllText(path, sb.ToString());

    }

The result would be:

Hello   Foo     World
1       3       3
2       4       4
4       7       7