Random number generator with or without weights.

Random bool, String, double, or other data types.

randomInt

Similar to Random().nextInt but can add a lower bound.

Random int that is >= -3 and < 2:

int i =randomInt(-3, 2);

All functions can pass a particular Random object. onResult callback executes after the number is generated:

int balance =100;
int gamble =randomInt(
-100,
101,
random:Random.secure(),
onResult: (result) {
balance += result;
print('Random int: $result');
print('Current balance: $balance');
},
);
// Random int: -5// Current balance: 95

randomDouble

double n =randomDouble(-3, -2);
double n2 =randomDouble(
-3,
-2,
random:Random(1), // always the same answer since seed is given
onResult: (result) {
print(result);
},
);
// -2.4214987135587918

weighted, weightedList

weighted returns a random element from an iterable, so elements are weighted by how many occurrences of each element:

// 3/4 chance of 1, 1/4 chance of 2int i =weighted([1, 1, 1, 2]);
// toSet() gets rid of duplicates, so now it's 50-50int j =weighted([1, 1, 1, 2].toSet());
int k =weighted(
[1, 1, 1, 2],
random:Random.secure(),
onResult: (result) =>print('Result is $result'),
);
// Result is 1

weightedList can specify length to return a List.

(onEachValue is called after generating each value, onFullResult is called once after generating the List.)

List<int> l =weightedList([1, 1, 2], length:10);
// Example result: [1, 1, 1, 1, 2, 1, 1, 1, 1, 2]List<String> l2 =weightedList(
['hello', 'world'],
length:5,
random:Random.secure(),
onEachValue: (index, value) =>print("You got '$value' at index $index"),
onFullResult: (result) =>print(result),
);
/*You got 'world' at index 0You got 'hello' at index 1You got 'world' at index 2You got 'hello' at index 3You got 'hello' at index 4[world, hello, world, hello, hello]*/

The heart package can be used to generate lists to use as arguments:

// Same as weightedList([0, 2,..., 98, 0, 2,..., 98, 1, 3,..., 99]);List<int> l =weightedList(range(0, 100, 2) *2+range(1, 100, 2), length:20);
// [10, 35, 67, 82, 2, 9, 98, 53, 72, 98, 74, 19, 73, 4, 38, 85, 53, 34, 64, 94]

weightedFromMap, weightedListFromMap

Weights can be given as values in a Map.

weightedFromMap returns one value:

// 1/3 chance of 0, 2/3 chance of 1int i =weightedFromMap({0:1, 1:2});
// 4/9 chance of 0, 1, or 2; 5/9 chance of 3, 4, or 5int j =weightedFromMap({randomInt(0, 3):4, randomInt(3, 6):5});
// This will return 'hello' since 'world' has 0 weightString s =weightedFromMap(
{'hello':1, 'world':0},
random:Random.secure(),
onResult: (result) {
print(result);
},
);

weightedListFromMap can specify length to return a List:

int balance =0;
List<int> l =weightedListFromMap(
{1:2, -1:1},
length:5,
random:Random.secure(),
onEachValue: (index, value) {
print('You got $value at index $index');
balance += value;
},
onFullResult: (result) =>print('Final balance after $result is: $balance'),
);
/*You got 1 at index 0You got 1 at index 1You got -1 at index 2You got 1 at index 3You got -1 at index 4Final balance after [1, 1, -1, 1, -1] is: 1*/

weightedBool

With no arguments, it gives 50/50 odds:

bool b =weightedBool();

With optional arguments:

int balance =100;
// 3/5 chance of truebool b =weightedBool(
trueWeight:3,
falseWeight:2,
random:Random.secure(),
onTrue: () => balance +=100,
onFalse: () => balance -=100,
onResult: (result) =>print('Result: $result\nBalance: $balance'),
);
/*Result: trueBalance: 200*/

weightedString

Returns a random String from the characters in a given String. Weights are given by number of occurrences in the given String.

// 3/4 chance of 'á', 1/4 chance of 'é'String s =weightedString('áááé'); // 'á', default length is 1String s2 =weightedString('áéíóú', length:10); // óáéóéáóíúí

Constants are given to help generate random Strings:

const kPrintableCharacters =' !"#\$%&\'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~';
const kPrintableCharactersWithoutSpace ='!"#\$%&\'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~';
const kDigits ='0123456789';
const kUppercaseLetters ='ABCDEFGHIJKLMNOPQRSTUVWXYZ';
const kLowercaseLetters ='abcdefghijklmnopqrstuvwxyz';
const kLetters = kUppercaseLetters + kLowercaseLetters;
const kAlphanumeric = kLetters + kDigits;

String s =weightedString(
kPrintableCharacters,
length:5,
random:Random.secure(),
onEachCharacter: (index, c) =>print('$c at index $index'),
onFullResult: (result) =>print(result),
);
/*x at index 0w at index 1- at index 2l at index 3j at index 4xw-lj*/