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QuickStart Samples

# Data Frames QuickStart Sample (C#)

Illustrates how to create and manipulate data frames using classes in the Extreme.DataAnalysis namespace in C#.

View this sample in: Visual Basic F#

``````using System;
using System.Collections.Generic;

using Extreme.Data.Text;

using Extreme.DataAnalysis;
using Extreme.Mathematics;

using Index = Extreme.DataAnalysis.Index;

namespace Extreme.Numerics.QuickStart.CSharp
{
/// <summary>
/// Illustrates how to create and manipulate data frames.
/// </summary>
class DataFrames
{
static void Main(string[] args)
{
// The license is verified at runtime. We're using
// https://www.extremeoptimization.com/trialkey

// Data frames can be constructed in a variety of ways.
// This example will use mostly static methods of the
// static DataFrame class.

// From a dictionary of column keys that map to collections:
var data = new Dictionary<string, object>() {
{ "state", new string[] { "Ohio", "Ohio", "Ohio", "Nevada", "Nevada" } },
{ "year", new int[] { 2000, 2001, 2002, 2001, 2002 } },
{ "pop", new double[] { 1.5, 1.7, 3.6, 2.4, 2.9 } }
};
var df1 = DataFrame.FromColumns(data);
Console.WriteLine(df1);

// The data frame has a default index of row numbers.
// A row index can be specified as well:
var df2 = DataFrame.FromColumns(new Dictionary<string, object>() {
{ "first", new double[] { 11, 14, 17, 93, 55 } },
{ "second", new double[] { 22, 33, 43, 51, 69 } } },
Index.CreateDateRange(new DateTime(2015, 4, 1), 5));
Console.WriteLine(df2);

// Alternatively, the columns can be a list of collections.
var rowIndex = Index.Create(new[] { "one", "two", "three", "four", "five" });
var df3 = DataFrame.FromColumns(data, rowIndex);
Console.WriteLine(df3);
// If you supply a column index, only the columns with
// keys in the index will be retained:
var columnIndex = Index.Create(new[] { "pop", "year" });
var df4 = DataFrame.FromColumns(data, rowIndex, columnIndex);
Console.WriteLine(df4);

// Yet another way is to use tuples:
var df5 = DataFrame.FromColumns(
("year", (object)new int[] { 2000, 2001, 2002, 2001, 2002 }),
("pop", (object)new double[] { 1.5, 1.7, 3.6, 2.4, 2.9 }));
Console.WriteLine(df5);

// Data frames can be created from a sequence of objects.
// By default, all public properties are included as columns
// in the resulting data frame:
var points = new[]
{
new { X = 1, Y = 5, Z = 9 },
new { X = 2, Y = 6, Z = 10 },
new { X = 3, Y = 7, Z = 11 },
new { X = 4, Y = 8, Z = 12 }
};
var df6 = DataFrame.FromObjects(points);
Console.WriteLine(df6);
// It is possible to select the properties:
var df7 = DataFrame.FromObjects(points, new[] { "Z", "X" });
Console.WriteLine(df7);

// Vectors and matrices can be converted to data frames
// using their ToDataFrame method:
var m = Matrix.CreateRandom(10, 2);
var df8 = m.ToDataFrame(Index.Default(10), Index.Create(new[] { "A", "B" }));
var v = Vector.CreateRandom(3);
var df9 = v.ToDataFrame(Index.Create(new[] { "a", "b", "c" }), "values");

//
// Import / export
//

// Several methods exist for importing data frames directly
// from data sources like text files, R data files, and databases.
var dt = new System.Data.DataTable();
dt.Rows.Add(new object[] { 1.0, 2.0 });
dt.Rows.Add(new object[] { 3.0, 4.0 });
dt.Rows.Add(new object[] { 5.0, 6.0 });
var df11 = DataFrame.FromDataTable(dt);

const string path = @"..\..\..\..\data\";
var df12 = DelimitedTextFile.ReadDataFrame(path + "iris.csv",
// By default, these methods return a data frame with a default
// index (row numbers). You can specify the column(s) to use
// for the index, and the data frame will use that column.
var df13 = DelimitedTextFile.ReadDataFrame<int>(path + "titanic.csv",
"PassengerId", options: DelimitedTextOptions.Csv);
DelimitedTextFile.Write("irisCopy.csv", df12, DelimitedTextOptions.Csv);

//
// Setting row and column indexes
//

// You can use specific columns as the row index.
// Here we have a 2 level hierarchical index:
var df1a = df1.WithRowIndex<string, int>("state", "year");

/// Column indexes can be changed as well:
var df2b = df2.WithColumnIndex(new string[] { "A", "B" });

Console.Write("Press any key to exit.");