mutoo
7/6/2013 - 6:45 PM

By counting the distribution of numbers after simple shuffle, statistics indicate that the probability of distribution of numbers is inequ

By counting the distribution of numbers after simple shuffle, statistics indicate that the probability of distribution of numbers is inequality；

worse_shuffle.js
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var numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
var total = [];
var testCount = 10000;

for (var i = 0; i < numbers.length; i++) {
  total[i] = [];
	for (var j = 0; j < numbers.length; j++) {
		total[i][j] = 0;
	}
};

var randomize = function(a,b){
	return Math.random()<0.5?-1:1;
}

for (var j = 0; j < testCount; j++) {
	num = [].concat(numbers);
	num.sort(randomize);
	for (var i = 0; i < num.length; i++) {
		var index = num.indexOf(i);
		total[i][index]++;
	}
}
console.log(total.join("\n"));

/*
2886,2917,1962,1115,562,297,145,57,45,14
2999,2815,1896,1081,593,297,175,83,40,21
1878,1919,2271,1734,1049,561,306,144,96,42
1050,1147,1694,2199,1756,1047,564,303,162,78
575,593,1016,1705,2181,1712,1120,606,353,139
324,311,613,1002,1713,2303,1766,1065,603,300
158,162,285,626,1062,1785,2296,1866,1131,629
65,79,157,303,588,1059,1856,2634,1983,1276
44,40,77,145,338,620,1153,1980,3104,2499
21,17,29,90,158,319,619,1262,2483,5002
*/
simple_shuffle.js
content_copyfile_download
var numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
var total = [];
var testCount = 10000;

for (var i = 0; i < numbers.length; i++) {
	total[i] = [];
	for (var j = 0; j < numbers.length; j++) {
		total[i][j] = 0;
	}
};

for (var j = 0; j < testCount; j++) {
	num = [].concat(numbers);
	for (var i = 0; i < num.length; i++) {
		var n = Math.random() * num.length >> 0;
		var tmp = num[i];
		num[i] = num[n];
		num[n] = tmp;
	};
	for (var i = 0; i < num.length; i++) {
		var index = num.indexOf(i);
		total[i][index]++;
	}
}
console.log(total.join("\n"));
/*
1014,1006,962,973,995,1009,980,1020,1029,1012
1348,972,1019,912,926,967,971,908,996,981
1165,1233,872,985,855,939,964,915,1008,1064
1115,1149,1222,814,922,916,929,926,983,1024
1063,1068,1112,1161,870,869,903,979,944,1031
949,1036,1075,1141,1192,828,881,955,958,985
888,954,990,1086,1098,1184,923,947,909,1021
883,873,936,1010,1131,1146,1196,920,983,922
790,872,950,953,1045,1101,1169,1206,934,980
785,837,862,965,966,1041,1084,1224,1256,980
/*
better_shuffle.js
content_copyfile_download
var numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
var total = [];
var testCount = 10000;
 
for (var i = 0; i < numbers.length; i++) {
	total[i] = [];
	for (var j = 0; j < numbers.length; j++) {
		total[i][j] = 0;
	}
};
 
for (var j = 0; j < testCount; j++) {
	num = [].concat(numbers);
	for (var i = 0; i < num.length; i++) {
		var n = i+Math.random() * (num.length-i) >> 0;
		var tmp = num[i];
		num[i] = num[n];
		num[n] = tmp;
	};
	for (var i = 0; i < num.length; i++) {
		var index = num.indexOf(i);
		total[i][index]++;
	}
}
console.log(total.join("\n"));
/*
955,1033,985,990,1016,982,983,1012,1012,1032
1051,968,1000,1041,1007,977,961,994,1006,995
972,1034,1005,985,998,1006,983,996,999,1022
1021,1007,998,977,1003,1003,1014,1034,959,984
977,1002,1018,1008,977,980,983,1026,1044,985
1085,947,995,1012,977,971,1018,969,984,1042
954,1041,994,996,1036,1023,997,975,983,1001
1007,1015,988,979,1023,990,993,1026,1040,939
991,971,998,1037,1001,1048,996,994,953,1011
987,982,1019,975,962,1020,1072,974,1020,989
*/