All Questions
Tagged with probability java
215
questions
140
votes
3
answers
10k
views
Why does this random value have a 25/75 distribution instead of 50/50?
Edit: So basically what I'm trying to write is a 1 bit hash for double.
I want to map a double to true or false with a 50/50 chance. For that I wrote code that picks some random numbers (just as an ...
- 19.3k
76
votes
13
answers
72k
views
How to pick an item by its probability?
I have a list of items. Each of these items has its own probability.
Can anyone suggest an algorithm to pick an item based on its probability?
- 9,816
68
votes
11
answers
86k
views
Random number with Probabilities
I am wondering what would be the best way (e.g. in Java) to generate random numbers within a particular range where each number has a certain probability to occur or not?
e.g.
Generate random ...
- 5,846
54
votes
7
answers
306k
views
How to calculate mean, median, mode and range from a set of numbers
Are there any functions (as part of a math library) which will calculate mean, median, mode and range from a set of numbers.
- 12.8k
44
votes
5
answers
88k
views
Probability in Java
I was curious to know, how do I implement probability in Java? For example, if the chances of a variable showing is 1/25, then how would I implement that? Or any other probability? Please point me in ...
- 3,294
30
votes
8
answers
14k
views
Random boolean with weight or bias
I need to generate some random booleans. However I need to be able to specify the probability of returning true. As a results doing:
private Random random = new Random();
random.nextBoolean();
will ...
- 2,040
23
votes
5
answers
47k
views
Algorithm to generate Poisson and binomial random numbers?
i've been looking around, but i'm not sure how to do it.
i've found this page which, in the last paragraph, says:
A simple generator for random numbers taken from a Poisson distribution is obtained ...
snap
19
votes
6
answers
12k
views
Generating N numbers that sum to 1
Given an array of size n I want to generate random probabilities for each index such that Sigma(a[0]..a[n-1])=1
One possible result might be:
0 1 2 3 4
0.15 0.2 0.18 0.22 0.25
...
- 163k
19
votes
4
answers
14k
views
Calculate the number of ways to roll a certain number
I'm a high school Computer Science student, and today I was given a problem to:
Program Description: There is a belief among dice players that in
throwing three dice a ten is easier to get than ...
- 7,328
18
votes
2
answers
2k
views
Effective Java Item 47: Know and use your libraries - Flawed random integer method example
In the example Josh gives of the flawed random method that generates a positive random number with a given upper bound n, I don't understand the two of the flaws he states.
The method from the book ...
- 313
18
votes
3
answers
776
views
How was there no collision among 50,000 random 7-digit hex strings? (The Birthday Problem)
I've encountered some code that generates a number of UUIDs via UUID.randomUUID(), takes the last 7 digits of each (recent versions of UUID are uniformly distributed in terms of entropy), and uses ...
- 29.8k
14
votes
6
answers
3k
views
Implementation of a simple algorithm (to calculate probability)
I've been asked (as part of homework) to design a Java program that does the following:
Basically there are 3 cards:
Black coloured on both sides
Red coloured on both sides
Black on one side, red on ...
- 143
11
votes
5
answers
25k
views
Which java-library computes the cumulative standard normal distribution function?
For a project I have a specification with formulas, I have to implement. In these formulas a cumulative standard normal distribution function exists, that takes a float and outputs a probability. The ...
- 50.9k
10
votes
6
answers
6k
views
Java double and working with really small values
I have to store the product of several probabilty values that are really low (for example, 1E-80). Using the primitive java double would result in zero because of the underflow. I don't want the value ...
- 125
10
votes
1
answer
607
views
Space-efficient probabilistic data structures for number retrieval
Consider we have an algorithm that receives a hypothetically long stream of keys. It then generates a value between 0 and 1 for each key, as we process it, for posterior retrieval. The input set is ...
- 93.9k
8
votes
4
answers
5k
views
Discrete Probability Distribution in Java
I have a set of integers each of which has a probability assigned, derived from earlier experiments, e.g.:
0 = 0.5
1 = 0.2
2 = 0.3
Complying with the specifications of a probability distribution, ...
- 1,952
8
votes
2
answers
4k
views
Algorithm for calculating probabilities of a number being drawn opening a book
I have a book with N<10000 pages, and a number x(in the range 1<=x<=40).
I want to calculate the probability that, opening that book at random, the combination of the digits of the opened ...
- 3,053
7
votes
2
answers
9k
views
Generating random integers within range with a probability distribution
I have a problem where I want to generate a set of random integer values between 1 and 5 inclusive using a probability distribution.
Poisson and Inverse Gamma are two distributions that show the ...
- 620
7
votes
3
answers
10k
views
Implement probability distribution function in Java problem
I have a function which is in the form of probability distribution function as below:
Although I discover some lib providing function to obtain the result as the above formula would do; but I am ...
- 71
6
votes
2
answers
719
views
Time efficient implementation of generating probability tree and then sorting the results
I have some events, where each of them has a probability to happen, and a weight if they do. I want to create all possible combinations of probabilities of events, with the corresponding weights. In ...
- 63
6
votes
4
answers
7k
views
Implementing probability distribution function in Java
I'm trying to implement a probability distribution function in java where it returns the ith entry in the array with probability:
Fi = 6i(n-i) / (n3 - n)
where n is the array length i.e. for an ...
- 197
6
votes
1
answer
404
views
java random string generation and birthday paradox
i need to write a random string generation class which generates 7char strings from a 31-char charset of numbers and some alphabets (10+26-5 , 5 vowels omitted). simple maths gives a set of 31^7 ...
- 1,475
5
votes
3
answers
182
views
Under what circumstances that you would want to have a different seed for you random number generator?
I am wondering under what circumstances that you would want to have a different seed for you random number generator. I see code somewhere that people create a Random object every time when needed, ...
- 8,383
5
votes
4
answers
1k
views
Estimating a probability given other probabilities from a prior
I have a bunch of data coming in (calls to an automated callcenter) about whether or not a person buys a particular product, 1 for buy, 0 for not buy.
I want to use this data to create an estimated ...
- 35.5k
4
votes
3
answers
5k
views
Generate random number between 0 and 1 with (negative)exponential distribution
Heyho,
I'm trying to generate a random number between 0.0 and 1.0 with exponential/negative exponential distribution. There is an article, which tells that you have to get the "quantile function". ...
- 1,028
4
votes
2
answers
5k
views
How to compute the probability of a multi-class prediction using libsvm?
I'm using libsvm and the documentation leads me to believe that there's a way to output the believed probability of an output classification's accuracy. Is this so? And if so, can anyone provide a ...
- 17.8k
4
votes
1
answer
624
views
Java- Math.random(): Selecting an element of a 13 by 13 triangular array
Edit: This problem is solved. If you would like to help on another problem, please visit Java Biasing Random Numbers in a Triangular Array.
I'm doing a multiplication game, so I pick 2 numbers ...
- 24.7k
4
votes
6
answers
176
views
Is BigInteger#nextProbablePrime accurate up to, at least, 64-bit numbers?
I'm looking to generate prime numbers using BigInteger#nextProbablePrime. The documentation of this method states the following:
The probability that the number returned by this method is composite ...
- 29.3k
4
votes
2
answers
2k
views
is it safe to use string hashcode as etag
Given a certain input parameter, for a rest api i want to use the hashcode as etag.
What is the probability that the json response has changed and the hashcode will be the same?
Alternatively is ...
- 7,219
4
votes
1
answer
727
views
Numerical accuracy with log probability Java implementation
Sometimes when you do calculations with very small probabilities using common data types such as doubles, numerical inaccuracies cascade over multiple calculations and lead to incorrect results. ...
- 5,102
3
votes
4
answers
930
views
Algorithm for probability over 100%
I am in need of an algorithm (in Java, but the theory should be pretty general) for some sort of probability... thing. I don't even know what to call it, which is why I haven't had any luck Googling.
...
- 2,510
3
votes
5
answers
12k
views
Monty Hall Game
I'm a new programmer currently in the process of learning Java. I've got a game here based on the game Let's make a deal & the monty hall problem (https://www.youtube.com/watch?v=mhlc7peGlGg) and ...
- 39
3
votes
3
answers
920
views
How to generate a set of values that follow certain distribution in c++/java?
For example, I have a p.d.f f(x) = 1/25 - x/1250 (from x = 0 to 50);
My question is that how to generate a set of values that satisfy the given p.d.f.
Please give an idea about how to implement in c++ ...
- 33
3
votes
3
answers
448
views
Why is my simulation not finding infinite expected value?
In the Youtube video Numberphile Infinity (starting at 6:09) there is an experiment described (the St. Petersburg Paradox) in which a game has infinite expected value.
I tried to write a Java program ...
- 33
3
votes
1
answer
5k
views
Generating a unique ID for every request in a distributed system
I'm trying to generate a unique id for each request in a DS. I'm thinking of concatenating a random integer and timestamp of the request's receipt. Since, getting a random integer can result in ...
- 3,552
3
votes
3
answers
1k
views
Randomly selecting points in a plane, with a higher probability of selection given to closer points
I've got a problem I'm not too sure how to solve. I have a 2d space with several points in it. I also have a current point, which is one of the points in the space. I want to randomly select one of ...
- 1,064
3
votes
2
answers
665
views
Rating Articles - Sentiment Analysis [closed]
I am working on a Java program(classifier) which reads a given text file and outputs the related sentiment (Positive or Negative or Neutral).
The program calculates three probabilities for the three ...
- 5,587
3
votes
2
answers
2k
views
Compute probability over a multivariate normal
My question addresses both mathematical and CS issues, but since I need a performant implementation I am posting it here.
Problem:
I have an estimated normal bivariate distribution, defined as a ...
- 555
3
votes
1
answer
71
views
Java random intersection in a range: unexpected results
Please consider this piece of code:
private static final Random RANDOM = new Random();
public static void main(String[] args) {
long distinct = IntStream.range(0, 600)
....
- 1,658
3
votes
3
answers
4k
views
Dice Sum Probability with Different types of Dice
I am currently working on a java application where I need to calculate the probabilities of rolling each sum for a variety of dice. The dice types I am supporting are d4 (4 sided dice), d6 (6 sided ...
- 922
3
votes
4
answers
13k
views
How do I generate normal cumulative distribution in Java? its inverse cdf? How about lognormal?
I am brand new to Java, second day! I want generate samples with normal distribution. I am using inverse transformation.
Basically, I want to find the inverse normal cumulative distribution, then ...
- 191
3
votes
2
answers
533
views
I need an efficient algorithm and/or code for a modelling Poisson distribution of a system
eeesh that title isn't very good.
Here is the situation.
I have a simulation that runs in real time, I'm trying to efficiently simulate a random count rate that has a known expectation value over a ...
- 2,726
3
votes
4
answers
1k
views
How to calculate the probability of getting the sum X using N six-sided dice
The Challenge:
For example, what is the probability of getting the sum of 15 when using 3 six-sided dice. This can be for example by getting 5-5-5 or 6-6-3 or 3-6-6 or many more options.
A brute force ...
- 6,706
3
votes
2
answers
92
views
Checking if 20 random booleans have the same value
I am trying to generate 20 random booleans and see if they have the same value i.e. either all true or all false. I expected the program to run for a while as the probability should be 1/(2^20) *100 * ...
- 1,396
3
votes
1
answer
690
views
How to programmatically calculate a discrete probabilities
I am using EnumeratedIntegerDistribution to generated samples from my set of keys.
How to programmatically calculate a 'discrete probabilities' array.
for example I might want an approximate 'normal' ...
- 401
3
votes
2
answers
442
views
Calculating average in a TestLuck (Probability) Program
I'm a student, trying to write a program that tests probability. It's called TestLuck it's supposed to generate a user determined amount of IntArrayLogs(ADT's) that are populated with random values. ...
- 635
3
votes
2
answers
463
views
Are there any implementations of Subjective Logic based trust metrics out there? [closed]
Subjective Logic is fundamental as part of my next project, and I was just wondering if there are any implementations already out there. I've read some things (not a lot) about the operators but I'm ...
- 14.3k
2
votes
3
answers
20k
views
Java: How do I simulate probability?
I have a set of over 100 different probabilities ranging from 0.007379 all the way to 0.913855 (These probabilities were collected from an actuary table http://www.ssa.gov/oact/STATS/table4c6.html). ...
- 1,644
2
votes
1
answer
4k
views
Get risk predictions in WEKA using own Java code
I already checked the "Making predictions" documentation of WEKA and it contains explicit instructions for command line and GUI predictions.
I want to know how to get a prediction value like the one ...
user1685185
2
votes
3
answers
12k
views
How do you generate a random number with equal probability using Math.random() in Java [duplicate]
I'm currently working through an exercise where I am required to generate a random number which can be one of 4 values. (note I'm only allowed to use Math.random())
0
1
2
or 3
Currently I am using ...
- 129