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【C#】配列やリストから目的の値に最も近い値を取得する拡張メソッドその2

C# C# - 拡張メソッド

ソースコード

using System;
using System.Collections.Generic;
using System.Linq;

public static class IEnumerableExtensions
{
   #region Nearest

    /// <summary>
    /// 目的の値に最も近い値を返します
    /// </summary>
    public static int Nearest( 
        this IEnumerable<int> self, 
        int target
    )
    {
        var min = self.Min( c => Math.Abs( c - target ) );
        return self.First( c => Math.Abs( c - target ) == min );
    }

    /// <summary>
    /// 目的の値に最も近い値を返します
    /// </summary>
    public static int Nearest<TSource>( 
        this IEnumerable<TSource> self, 
        int target, 
        Func<TSource, int> selector
    )
    {
        var min = self.Min( c => Math.Abs( selector( c ) - target ) );
        return selector( self.First( c => Math.Abs( selector( c ) - target ) == min ) );
    }

    /// <summary>
    /// 目的の値に最も近い値を持つ要素を返します
    /// </summary>
    public static TSource FindNearest<TSource>( 
        this IEnumerable<TSource> self, 
        int target, 
        Func<TSource, int> selector
    )
    {
        var min = self.Min( c => Math.Abs( selector( c ) - target ) );
        return self.First( c => Math.Abs( selector( c ) - target ) == min );
    }

   #endregion

   #region NearestMoreThan

    /// <summary>
    /// 目的の値に最も近く、目的の値より大きい値を返します
    /// </summary>
    public static int NearestMoreThan( 
        this IEnumerable<int> self, 
        int target
    )
    {
        var list = self.Where( c => target < c ).ToArray();
        var min = list.Min( c => Math.Abs( c - target ) );
        return list.First( c => Math.Abs( c - target ) == min );
    }

    /// <summary>
    /// 目的の値に最も近く、目的の値より大きい値を返します
    /// </summary>
    public static int NearestMoreThan<TSource>( 
        this IEnumerable<TSource> self, 
        int target, 
        Func<TSource, int> selector
    )
    {
        var list = self.Where( c => target < selector( c ) ).ToArray();
        var min = list.Min( c => Math.Abs( selector( c ) - target ) );
        return selector( list.First( c => Math.Abs( selector( c ) - target ) == min ) );
    }

    /// <summary>
    /// 目的の値に最も近く、目的の値より大きい値を持つ要素を返します
    /// </summary>
    public static TSource FindNearestMoreThan<TSource>( 
        this IEnumerable<TSource> self, 
        int target, 
        Func<TSource, int> selector
    )
    {
        var list = self.Where( c => target < selector( c ) ).ToArray();
        var min = list.Min( c => Math.Abs( selector( c ) - target ) );
        return list.First( c => Math.Abs( selector( c ) - target ) == min );
    }

   #endregion

   #region NearestOrMore

    /// <summary>
    /// 目的の値に最も近く、目的の値以上の値を返します
    /// </summary>
    public static int NearestOrMore( 
        this IEnumerable<int> self, 
        int target
    )
    {
        var list = self.Where( c => target <= c ).ToArray();
        var min = list.Min( c => Math.Abs( c - target ) );
        return list.First( c => Math.Abs( c - target ) == min );
    }

    /// <summary>
    /// 目的の値に最も近く、目的の値以上の値を返します
    /// </summary>
    public static int NearestOrMore<TSource>( 
        this IEnumerable<TSource> self, 
        int target, 
        Func<TSource, int> selector
    )
    {
        var list = self.Where( c => target <= selector( c ) ).ToArray();
        var min = list.Min( c => Math.Abs( selector( c ) - target ) );
        return selector( list.First( c => Math.Abs( selector( c ) - target ) == min ) );
    }

    /// <summary>
    /// 目的の値に最も近く、目的の値以上の値を持つ要素を返します
    /// </summary>
    public static TSource FindNearestOrMore<TSource>( 
        this IEnumerable<TSource> self, 
        int target, 
        Func<TSource, int> selector
    )
    {
        var list = self.Where( c => target <= selector( c ) ).ToArray();
        var min = list.Min( c => Math.Abs( selector( c ) - target ) );
        return list.First( c => Math.Abs( selector( c ) - target ) == min );
    }

   #endregion

   #region NearestOrLess

    /// <summary>
    /// 目的の値に最も近く、目的の値以下の値を返します
    /// </summary>
    public static int NearestOrLess( 
        this IEnumerable<int> self, 
        int target
    )
    {
        var list = self.Where( c => c <= target ).ToArray();
        var min = list.Min( c => Math.Abs( c - target ) );
        return list.First( c => Math.Abs( c - target ) == min );
    }

    /// <summary>
    /// 目的の値に最も近く、目的の値以下の値を返します
    /// </summary>
    public static int NearestOrLess<TSource>( 
        this IEnumerable<TSource> self, 
        int target, 
        Func<TSource, int> selector
    )
    {
        var list = self.Where( c => selector( c ) <= target ).ToArray();
        var min = list.Min( c => Math.Abs( selector( c ) - target ) );
        return selector( list.First( c => Math.Abs( selector( c ) - target ) == min ) );
    }

    /// <summary>
    /// 目的の値に最も近く、目的の値以下の値を持つ要素を返します
    /// </summary>
    public static TSource FindNearestOrLess<TSource>( 
        this IEnumerable<TSource> self, 
        int target, 
        Func<TSource, int> selector
    )
    {
        var list = self.Where( c => selector( c ) <= target ).ToArray();
        var min = list.Min( c => Math.Abs( selector( c ) - target ) );
        return list.First( c => Math.Abs( selector( c ) - target ) == min );
    }

   #endregion

   #region NearestMoreLess

    /// <summary>
    /// 目的の値に最も近く、目的の値より小さい値を返します
    /// </summary>
    public static int NearestMoreLess( 
        this IEnumerable<int> self, 
        int target
    )
    {
        var list = self.Where( c => c < target ).ToArray();
        var min = list.Min( c => Math.Abs( c - target ) );
        return list.First( c => Math.Abs( c - target ) == min );
    }

    /// <summary>
    /// 目的の値に最も近く、目的の値より小さい値を返します
    /// </summary>
    public static int NearestMoreLess<TSource>( 
        this IEnumerable<TSource> self, 
        int target, 
        Func<TSource, int> selector
    )
    {
        var list = self.Where( c => selector( c ) < target ).ToArray();
        var min = list.Min( c => Math.Abs( selector( c ) - target ) );
        return selector( list.First( c => Math.Abs( selector( c ) - target ) == min ) );
    }

    /// <summary>
    /// 目的の値に最も近く、目的の値より小さい値を持つ要素を返します
    /// </summary>
    public static TSource FindNearestMoreLess<TSource>( 
        this IEnumerable<TSource> self, 
        int target, 
        Func<TSource, int> selector
    )
    {
        var list = self.Where( c => selector( c ) < target ).ToArray();
        var min = list.Min( c => Math.Abs( selector( c ) - target ) );
        return list.First( c => Math.Abs( selector( c ) - target ) == min );
    }

   #endregion
}

使い方

var list = new []{ 1, 2, 4, 8, 16 };

var target = 5;
Debug.Log( list.Nearest( target ) );            // 4
Debug.Log( list.NearestMoreThan( target ) );    // 8
Debug.Log( list.NearestOrMore( target ) );      // 8
Debug.Log( list.NearestOrLess( target ) );      // 4
Debug.Log( list.NearestMoreLess( target ) );    // 4

target = 8;
Debug.Log( list.Nearest( target ) );            // 8
Debug.Log( list.NearestMoreThan( target ) );    // 16
Debug.Log( list.NearestOrMore( target ) );      // 8
Debug.Log( list.NearestOrLess( target ) );      // 8
Debug.Log( list.NearestMoreLess( target ) );    // 4

関数一覧

関数名	説明
Nearest	目的の値に最も近い値を返します
NearestMoreThan	目的の値に最も近く、目的の値より大きい値を返します
NearestOrMore	目的の値に最も近く、目的の値以上の値を返します
NearestOrLess	目的の値に最も近く、目的の値以下の値を返します
NearestMoreLess	目的の値に最も近く、目的の値より小さい値を返します

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