C# Deedle equivalent to pandas df.drop_duplicates?

Question

In Python pandas, I can easily drop duplicates in a DataFrame with:

df1.drop_duplicates(['Service Date', 'Customer Number'], inplace=True)

Is there anything in C# or Deedle that's this simple and fast? Or do I need to iterate over the entire frame (from a large CSV file) to drop duplicates?

The data I'm working with is imported from a large CSV file with about 40 columns and 12k rows. For each date, there are multiple entries for Customer Number. I need to eliminate duplicate Customer Number rows (leaving only one unique) per date.

Here's some simplified data, using DATE and RECN as the columns used to de-dupify:

NAME,       TYPE,  DATE,      RECN,  COMM
Kermit,     Frog,  06/30/14,  1,     1test
Kermit,     Frog,  06/30/14,  1,     2test
Ms. Piggy,  Pig,   07/01/14,  2,     1test
Fozzy,      Bear,  06/29/14,  3,     1test
Kermit,     Frog,  07/02/14,  1,     3test
Kermit,     Frog,  07/02/14,  1,     4test
Kermit,     Frog,  07/02/14,  1,     5test
Ms. Piggy,  Pig,   07/02/14,  2,     3test
Fozzy,      Bear,  07/02/14,  3,     2test
Ms. Piggy,  Pig,   07/02/14,  2,     2test

Added some simplified data. It's actually already sorted as-is, in the real data, wouldn't hurt to sort (the test data above isn't sorted). — user3478193, Jul 05 '14 at 23:29

mtmk · Answer 1 · 2014-07-06T14:20:36.100

Deedle doesn't seem to have that sort of utility in its CSV reader functions. Using another CSV reader to load the data (LumenWorks CSV Reader) I was able to de-duplicate the data using these extension methods:

public static class DeduplicateCsv
{
    public static IEnumerable<Series<string, object>> ReadCsv(this string file)
    {
        // NuGet: PM> Install-Package LumenWorksCsvReader
        using (var csv = new CsvReader(new StreamReader(file), true))
        {
            int fieldCount = csv.FieldCount;

            string[] headers = csv.GetFieldHeaders();
            while (csv.ReadNextRecord())
            {
                var seriesBuilder = new SeriesBuilder<string>();
                for (int i = 0; i < fieldCount; i++)
                {
                    seriesBuilder.Add(headers[i], csv[i]);
                }
                yield return seriesBuilder.Series;
            }
        }
    }

    public static IEnumerable<TSource> DistinctObject<TSource, TCompare>(this IEnumerable<TSource> source, Func<TSource, TCompare> compare)
    {
        var set = new HashSet<TCompare>();
        return source.Where(element => set.Add(compare(element)));
    }

    public static IEnumerable<Series<string, object>> DeDupify(this IEnumerable<Series<string, object>> source, string key)
    {
        return source.DistinctObject(s => s.Get(key));
    }
}

Here is how I used it:

var frame = Frame.FromRows("data.csv"
    .ReadCsv()
    .DeDupify("Service Date")
    .DeDupify("Customer Number")
    .ToList()
    );
frame.Print();

Note that I had to put a .ToList() at the end since Deedle seems to be running over the IEnumerable more than once.

C# Deedle equivalent to pandas df.drop_duplicates?

1 Answers1