Create advanced filter - excel

Question

I am trying to create an advanced filter in Excel from C# to copy unique data from one sheet to another, at least I get it in Excel and if I use Interop like this :
Excel.Range rang = sheet2.get_Range("A2");
Excel.Range oRng = sheet.get_Range("I2", "I" + (lst.Count + 1));
oRng.AdvancedFilter(Excel.XlFilterAction.xlFilterCopy, CriteriaRange: Type.Missing,
CopyToRange: rang, Unique: true);
Works fine but I'm doing all my application with EPPlus and it will be better if I can do the same without Interop.
So, it is possible?

Answer 1

Since Advanced Filter is an excel function you need the full Excel DOM to access it. Epplus doesnt have that - it just generated the XML to feed to excel which will then apply its "interpretation", so to speak.
But since you have the power of .NET at your disposal, you can use linq fairly easily to do the same thing by querying the cell store and using .distinct() to get the unique list. The only wrinkle is you have to create your own IEquitableComparer. This will do it:
[TestMethod]
public void Distinct_Filter_Test()
{
//Throw in some data
var datatable = new DataTable("tblData");
datatable.Columns.AddRange(new[]
{
new DataColumn("Col1", typeof (int)), new DataColumn("Col2", typeof (string))
});
var rnd = new Random();
for (var i = 0; i < 10; i++)
{
var row = datatable.NewRow();
row[0] = rnd.Next(1, 3) ;row[1] = i%2 == 0 ? "even": "odd";
datatable.Rows.Add(row);
}
//Create a test file
var fi = new FileInfo(#"c:\temp\Distinct_Filter.xlsx");
if (fi.Exists)
fi.Delete();
using (var pck = new ExcelPackage(fi))
{
//Load the random data
var workbook = pck.Workbook;
var worksheet = workbook.Worksheets.Add("data");
worksheet.Cells.LoadFromDataTable(datatable, true);
//Cells only contains references to cells with actual data
var rows = worksheet.Cells
.GroupBy(cell => cell.Start.Row)
.Skip(1) //Exclude header
.Select(cg => cg.Select(c => c.Value).ToArray())
.Distinct(new ArrayComparer())
.ToArray();
//Copy the data to the new sheet
var worksheet2 = workbook.Worksheets.Add("Distinct");
worksheet2.Cells.LoadFromArrays(rows);
pck.Save();
}
}
public class ArrayComparer: IEqualityComparer<object[]>
{
public bool Equals(object[] x, object[] y)
{
return !x.Where((o, i) => !o.Equals(y[i])).Any();
}
public int GetHashCode(object[] obj)
{
//Based on Jon Skeet Stack Overflow Post
unchecked
{
return obj.Aggregate((int) 2166136261, (acc, next) => acc*16777619 ^ next.GetHashCode());
}
}
}