How can I convert a data table in C# to data.fame in R using R.net

Question

I need to convert a data table which I have defined as follows to a data frame in R.

DataTable dtb = new DataTable();
            dtb.Columns.Add("Column1", Type.GetType("System.String"));
            dtb.Columns.Add("Column2", Type.GetType("System.String"));
            DataRow dtr1 = dtb.NewRow();
            dtr1[0] = "abc";
            dtr1[1] = "cdf";
            dtb.Rows.Add(dtr1);
            DataRow dtr2 = dtb.NewRow();
            dtr2[0] = "asdasd";
            dtr2[1] = "cdasdasf";
            dtb.Rows.Add(dtr2);

Is there any way to convert above DataTable "dtb" to a data.frame in R. I have defined this DataTable in C# but I need to do computation in R, that is why I need to pass it to R.

From what I can tell, it seems the best approach is to either convert the data table to a numeric matrix, or to convert it to a string. I haven't passed data from a C# application to R myself (yet), but it does seem that using C# strings as commands to the R engine is generally the best way to get commands and objects defined in the R environment. (see stackoverflow.com/questions/32022831/…; stackoverflow.com/questions/32029438/…). — Benjamin
– Benjamin, Commented Oct 20, 2015 at 11:20
Also, if at all possible, I'd recommend placing any data you may want to use in a database (MySQL, or some other) and then using R's RODBC package to pull the data into R. That seems like an approach that plays to the strengths of both programs. — Benjamin
– Benjamin, Commented Oct 20, 2015 at 11:21
@Benjamin, I converted DataTable to a string, but then how can I use it? — Artiga
– Artiga, Commented Oct 20, 2015 at 12:16
How about casting the DataTable to array and using the R.NET converter functions? github.com/jmp75/rdotnet/blob/master/R.NET/Utilities/… — Hansi
– Hansi, Commented Oct 20, 2015 at 20:17

Hansi · Accepted Answer · 2015-10-20 22:13:57Z

This worked in R.NET 1.6.5 and outputs:

Did not find a nice way of converting DataTable to string[,] as CreateCharacterMatrix expects but CreateDataFrame is an alternative possibility but that expects a IEnumerable[] and is column oriented (as data.frame in R is).

Going through the Tests in the source code might help further: https://github.com/jmp75/rdotnet/tree/master/RDotNet.Tests

There is also this: https://github.com/jmp75/rdotnet-onboarding

Which is in some ways more helpful because the official documentation is sparse: https://jmp75.github.io/rdotnet/getting_started/

using System;
using System.Data;
using RDotNet;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            DataTable dtb = new DataTable();
            dtb.Columns.Add("Column1", Type.GetType("System.String"));
            dtb.Columns.Add("Column2", Type.GetType("System.String"));
            DataRow dtr1 = dtb.NewRow();
            dtr1[0] = "abc";
            dtr1[1] = "cdf";
            dtb.Rows.Add(dtr1);
            DataRow dtr2 = dtb.NewRow();
            dtr2[0] = "asdasd";
            dtr2[1] = "cdasdasf";
            dtb.Rows.Add(dtr2);

            using (var engine = REngine.GetInstance())
            {
                string[,] stringData = new string[dtb.Rows.Count, dtb.Columns.Count];
                for (int row = 0; row < dtb.Rows.Count; row++)
                {
                    for (int col = 0; col < dtb.Columns.Count; col++)
                    {
                        stringData[row, col] = dtb.Rows[row].ItemArray[col].ToString();
                    }
                }
                CharacterMatrix matrix = engine.CreateCharacterMatrix(stringData);
                engine.SetSymbol("myRDataFrame", matrix);
                engine.Evaluate("myRDataFrame <- as.data.frame(myRDataFrame, stringsAsFactors = FALSE)");
                engine.Evaluate("str(myRDataFrame)");

            }
            Console.ReadKey();
        }
    }
}

Community · Accepted Answer · 2017-05-23 11:59:55Z

1

I think u can get your solution here.. Passing DataTable over COM into R This one has better explanation

edited May 23, 2017 at 11:59

CommunityBot

11 silver badge

answered Oct 20, 2015 at 11:32

Anshul Choure

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2 Comments

Artiga Over a year ago

Say, I get a string by converting DataTable to a string. Now how can I pass it to R.net. Because string is not acceptable. string csvfile= DataTableToCSV(dtb);

Benjamin Over a year ago

If you're able to make it a CSV, you should be able to read it into R with read.csv. If you've saved it to a file, you can use just plain read.csv. If you've saved it to a character string to pass as an object to R, you can use read.csv(textConnection(...))

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