# C# Stats Functions Example

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```using System;
using System.Collections;

using CenterSpace.NMath.Core;
using CenterSpace.NMath.Stats;
using System.IO;

namespace CenterSpace.NMath.Stats.Examples.CSharp
{
/// <summary>
/// A .NET example in C# showing how to use the descriptive statistics functions of the
/// StatsFunctions class.
/// </summary>
class StatsFunctionsExample
{

static void Main( string[] args )
{
// Read in data from a comma-delimited file. Data has age, gender, grade
// columns.

// Specify the data file, whether it includes headers, whether it has row keys,
// the delimiter, and whether to try to parse data into non-generic types.
DataFrame data = DataFrame.Load( "StatsFunctionsExample.dat", true, false, ",", true );

// Print out all data.
Console.WriteLine();
Console.WriteLine( data );
Console.WriteLine();

Console.WriteLine();

// How many male and female students are there?
IDictionary counts = StatsFunctions.Counts( data["Gender"] );
Console.Write( "There are " + counts["Male"] + " male students and " );
Console.WriteLine( counts["Female"] + " female students." );
Console.WriteLine();

Console.WriteLine();

// Is there a correlation between age and grade?
double correlation = StatsFunctions.Correlation( data["Age"], data["Grade"] );
if ( correlation > 0.0 )
{
Console.WriteLine( "There is a positive correlation of " + correlation.ToString( "F2" ) +
" between age and grade." );
Console.WriteLine();
}

// What percentage of students pass with a 50% passing rate?  60%?
Console.WriteLine( "Percentage passing with 50% cutoff: " +
( 1.0 - StatsFunctions.PercentileRank( data["Grade"], 50 ) ).ToString( "P2" ) );
Console.WriteLine( "Percentage passing with 50% cutoff: " +
( 1.0 - StatsFunctions.PercentileRank( data["Grade"], 60 ) ).ToString( "P2" ) );
Console.WriteLine();

// Percentiles
Console.WriteLine( "Interquartile range is " + StatsFunctions.InterquartileRange( data["Grade"] ) );
Console.WriteLine( "What's the 80th percentile? " + StatsFunctions.Percentile( data["Grade"], 0.8 ) );
Console.WriteLine();

// Split by gender and do descriptive statistics
Factor gender = data.GetFactor( "Gender" );
Subset[] genderGroups = Subset.GetGroupings( gender );
for ( int i = 0; i < genderGroups.Length; i++ )
{
DataFrame genderSpecific = data.GetRows( genderGroups[i] );
Console.WriteLine( gender.Levels[i] + " students..." );
Console.WriteLine();
}

// Young students
DataFrame young = data[new Subset( StatsFunctions.If( data["Age"],
new Func<double, bool>( Young ) ) ), Slice.All];
Console.WriteLine( "Young students..." );
Console.WriteLine();

// Top grade by a young student?
double top = StatsFunctions.MaxValue( young["Grade"] );
Console.WriteLine( "Top grade by a young student was... " + top );

// What percentage of the whole group beat the top-ranked young student?
Console.Write( "Percentage beating top-ranked young student... " );
Console.WriteLine( ( 1.0 - StatsFunctions.PercentileRank( data["Grade"], top ) ).ToString( "P2" ) );

Console.WriteLine();
Console.WriteLine( "Press Enter Key" );

}  // Main

private static bool Young( double age )
{
return age < 20.0;
}

}  // class

}  // namespace

```
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