jellyfin/MediaBrowser.Providers/Photos/PhotoHelper.cs

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3.8 KiB
C#
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2014-02-13 05:11:54 +00:00
using MediaBrowser.Controller.Entities;
using System;
using System.Collections.Generic;
using System.Text;
namespace MediaBrowser.Providers.Photos
{
public static class PhotoHelper
{
public static List<BaseItem> ShuffleList(List<BaseItem> list)
{
var rnd = new Random(DateTime.Now.Second);
for (var i = 1; i < list.Count; i++)
{
var pos = rnd.Next(i + 1);
var x = list[i];
list[i] = list[pos];
list[pos] = x;
}
return list;
}
public static string Dec2Frac(double dbl)
{
char neg = ' ';
double dblDecimal = dbl;
if (dblDecimal == (int)dblDecimal) return dblDecimal.ToString(); //return no if it's not a decimal
if (dblDecimal < 0)
{
dblDecimal = Math.Abs(dblDecimal);
neg = '-';
}
var whole = (int)Math.Truncate(dblDecimal);
string decpart = dblDecimal.ToString().Replace(Math.Truncate(dblDecimal) + ".", "");
double rN = Convert.ToDouble(decpart);
double rD = Math.Pow(10, decpart.Length);
string rd = Recur(decpart);
int rel = Convert.ToInt32(rd);
if (rel != 0)
{
rN = rel;
rD = (int)Math.Pow(10, rd.Length) - 1;
}
//just a few prime factors for testing purposes
var primes = new[] { 47, 43, 37, 31, 29, 23, 19, 17, 13, 11, 7, 5, 3, 2 };
foreach (int i in primes) ReduceNo(i, ref rD, ref rN);
rN = rN + (whole * rD);
return string.Format("{0}{1}/{2}", neg, rN, rD);
}
/// <summary>
/// Finds out the recurring decimal in a specified number
/// </summary>
/// <param name="db">Number to check</param>
/// <returns></returns>
private static string Recur(string db)
{
if (db.Length < 13) return "0";
var sb = new StringBuilder();
for (int i = 0; i < 7; i++)
{
sb.Append(db[i]);
int dlength = (db.Length / sb.ToString().Length);
int occur = Occurence(sb.ToString(), db);
if (dlength == occur || dlength == occur - sb.ToString().Length)
{
return sb.ToString();
}
}
return "0";
}
/// <summary>
/// Checks for number of occurence of specified no in a number
/// </summary>
/// <param name="s">The no to check occurence times</param>
/// <param name="check">The number where to check this</param>
/// <returns></returns>
private static int Occurence(string s, string check)
{
int i = 0;
int d = s.Length;
string ds = check;
for (int n = (ds.Length / d); n > 0; n--)
{
if (ds.Contains(s))
{
i++;
ds = ds.Remove(ds.IndexOf(s, System.StringComparison.Ordinal), d);
}
}
return i;
}
/// <summary>
/// Reduces a fraction given the numerator and denominator
/// </summary>
/// <param name="i">Number to use in an attempt to reduce fraction</param>
/// <param name="rD">the Denominator</param>
/// <param name="rN">the Numerator</param>
private static void ReduceNo(int i, ref double rD, ref double rN)
{
//keep reducing until divisibility ends
while ((rD % i) < 1e-10 && (rN % i) < 1e-10)
{
rN = rN / i;
rD = rD / i;
}
}
}
}