Split CSV files c#

Splitting logic of a CSV files into n number of files with .csv extension

Code Snippet:

for (int i = 1; i <= noOfFiles; i++)

{

    take = i == 1 ? finsPerCsv + mod : finsPerCsv;

    var fins = AllFins.GetRange(beginIndex, take);

    groupByfins.Add(fins);

    List<string> listw = masterData_raw.Where(item => col1Data.Any(category => category.col1.Equals(CSVParser2.Split(item)[0].Replace("\"", ""))));

    List<Items> list = masterData_cls.Where(item => col1Data.Any(category => category.col1.Equals(item.col1)));

   var csvFormattedData = list.Select(str =>

   "\"" + str.col1

   + "\",\"" + str.col2

   + "\",\"" + str.col3

   + "\",\"" + str.col4

   + "\",\"" + str.col5)

       .ToArray();

   csvHeader.CopyTo(csvFormattedData, 0);

   File.WriteAllLines(filepath, csvFormattedData);

   beginIndex = beginIndex + take;

}