using System;

namespace AForge.Math;

public static class Statistics
{
	public static double Mean(int[] values)
	{
		long num = 0L;
		double num2 = 0.0;
		int i = 0;
		for (int num3 = values.Length; i < num3; i++)
		{
			int num4 = values[i];
			num2 += (double)(i * num4);
			num += num4;
		}
		if (num != 0)
		{
			return num2 / (double)num;
		}
		return 0.0;
	}

	public static double StdDev(int[] values)
	{
		return StdDev(values, Mean(values));
	}

	public static double StdDev(int[] values, double mean)
	{
		double num = 0.0;
		int num2 = 0;
		int i = 0;
		for (int num3 = values.Length; i < num3; i++)
		{
			int num4 = values[i];
			double num5 = (double)i - mean;
			num += num5 * num5 * (double)num4;
			num2 += num4;
		}
		if (num2 != 0)
		{
			return System.Math.Sqrt(num / (double)num2);
		}
		return 0.0;
	}

	public static int Median(int[] values)
	{
		int num = 0;
		int num2 = values.Length;
		for (int i = 0; i < num2; i++)
		{
			num += values[i];
		}
		int num3 = num / 2;
		int j = 0;
		int num4 = 0;
		for (; j < num2; j++)
		{
			num4 += values[j];
			if (num4 >= num3)
			{
				break;
			}
		}
		return j;
	}

	public static IntRange GetRange(int[] values, double percent)
	{
		int num = 0;
		int num2 = values.Length;
		for (int i = 0; i < num2; i++)
		{
			num += values[i];
		}
		int num3 = (int)((double)num * (percent + (1.0 - percent) / 2.0));
		int j = 0;
		int num4 = num;
		for (; j < num2; j++)
		{
			num4 -= values[j];
			if (num4 < num3)
			{
				break;
			}
		}
		int num5 = num2 - 1;
		num4 = num;
		while (num5 >= 0)
		{
			num4 -= values[num5];
			if (num4 < num3)
			{
				break;
			}
			num5--;
		}
		return new IntRange(j, num5);
	}

	public static double Entropy(int[] values)
	{
		int num = values.Length;
		int num2 = 0;
		double num3 = 0.0;
		for (int i = 0; i < num; i++)
		{
			num2 += values[i];
		}
		if (num2 != 0)
		{
			for (int j = 0; j < num; j++)
			{
				double num4 = (double)values[j] / (double)num2;
				if (num4 != 0.0)
				{
					num3 += (0.0 - num4) * System.Math.Log(num4, 2.0);
				}
			}
		}
		return num3;
	}

	public static int Mode(int[] values)
	{
		int result = 0;
		int num = 0;
		int i = 0;
		for (int num2 = values.Length; i < num2; i++)
		{
			if (values[i] > num)
			{
				num = values[i];
				result = i;
			}
		}
		return result;
	}
}