| org.apache.commons.math.random.RandomData
All known Subclasses: org.apache.commons.math.random.RandomDataImpl,
| RandomData | | public interface RandomData (Code) | | Random data generation utilities.
version:
$Revision: 355770 $ $Date: 2005-12-10 12:48:57 -0700 (Sat, 10 Dec 2005) $ |
| Method Summary | |
| double | nextExponential(double mean)
Generates a random value from the exponential distribution
with expected value = mean. | | double | nextGaussian(double mu, double sigma)
Generates a random value from the
Normal (or Gaussian) distribution with the given mean
and standard deviation. | | String | nextHexString(int len)
Generates a random string of hex characters of length
len.
The generated string will be random, but not cryptographically
secure. | | int | nextInt(int lower, int upper)
Generates a uniformly distributed random integer between
lower and upper (endpoints included). | | long | nextLong(long lower, long upper)
Generates a uniformly distributed random long integer between
lower and upper (endpoints included). | | int[] | nextPermutation(int n, int k)
Generates an integer array of length k whose entries
are selected randomly, without repetition, from the integers
0 through n-1 (inclusive). | | long | nextPoisson(double mean)
Generates a random value from the Poisson distribution with
the given mean. | | Object[] | nextSample(Collection c, int k)
Returns an array of k objects selected randomly
from the Collection c.
Sampling from c
is without replacement; but if c contains identical
objects, the sample may include repeats. | | String | nextSecureHexString(int len)
Generates a random string of hex characters from a secure random
sequence. | | int | nextSecureInt(int lower, int upper)
Generates a uniformly distributed random integer between
lower and upper (endpoints included)
from a secure random sequence.
Sequences of integers generated using this method will be
cryptographically secure. | | long | nextSecureLong(long lower, long upper)
Generates a random long integer between lower
and upper (endpoints included).
Sequences of long values generated using this method will be
cryptographically secure. | | double | nextUniform(double lower, double upper)
Generates a uniformly distributed random value from the open interval
(lower,upper) (i.e., endpoints excluded). |
| nextExponential | | double nextExponential(double mean)(Code) | | Generates a random value from the exponential distribution
with expected value = mean.
Definition:
Exponential Distribution
Preconditions:
mu >= 0 (otherwise an IllegalArgumentException
is thrown.)
Parameters:
mean - Mean of the distribution random value from exponential distribution |
| nextGaussian | | double nextGaussian(double mu, double sigma)(Code) | | Generates a random value from the
Normal (or Gaussian) distribution with the given mean
and standard deviation.
Definition:
Normal Distribution
Preconditions:
sigma > 0 (otherwise an IllegalArgumentException
is thrown.)
Parameters:
mu - Mean of the distribution
Parameters:
sigma - Standard deviation of the distribution random value from Gaussian distribution with mean = mu,standard deviation = sigma |
| nextHexString | | String nextHexString(int len)(Code) | | Generates a random string of hex characters of length
len.
The generated string will be random, but not cryptographically
secure. To generate cryptographically secure strings, use
nextSecureHexString
Preconditions:
len > 0 (otherwise an IllegalArgumentException
is thrown.)
Parameters:
len - the length of the string to be generated random string of hex characters of length len |
| nextInt | | int nextInt(int lower, int upper)(Code) | | Generates a uniformly distributed random integer between
lower and upper (endpoints included).
The generated integer will be random, but not cryptographically secure.
To generate cryptographically secure integer sequences, use
nextSecureInt.
Preconditions:
lower < upper (otherwise an IllegalArgumentException
is thrown.)
Parameters:
lower - lower bound for generated integer
Parameters:
upper - upper bound for generated integer a random integer greater than or equal to lowerand less than or equal to upper. |
| nextLong | | long nextLong(long lower, long upper)(Code) | | Generates a uniformly distributed random long integer between
lower and upper (endpoints included).
The generated long integer values will be random, but not
cryptographically secure.
To generate cryptographically secure sequences of longs, use
nextSecureLong
Preconditions:
lower < upper (otherwise an IllegalArgumentException
is thrown.)
Parameters:
lower - lower bound for generated integer
Parameters:
upper - upper bound for generated integer a random integer greater than or equal to lowerand less than or equal to upper. |
| nextPermutation | | int[] nextPermutation(int n, int k)(Code) | | Generates an integer array of length k whose entries
are selected randomly, without repetition, from the integers
0 through n-1 (inclusive).
Generated arrays represent permutations
of n taken k at a time.
Preconditions:
If the preconditions are not met, an IllegalArgumentException is
thrown.
Parameters:
n - domain of the permutation
Parameters:
k - size of the permutation random k-permutation of n |
| nextPoisson | | long nextPoisson(double mean)(Code) | | Generates a random value from the Poisson distribution with
the given mean.
Definition:
Poisson Distribution
Preconditions:
- The specified mean must be positive (otherwise an
IllegalArgumentException is thrown.)
Parameters:
mean - Mean of the distribution poisson deviate with the specified mean |
| nextSample | | Object[] nextSample(Collection c, int k)(Code) | | Returns an array of k objects selected randomly
from the Collection c.
Sampling from c
is without replacement; but if c contains identical
objects, the sample may include repeats. If all elements of
c are distinct, the resulting object array represents a
Simple Random Sample of size
k from the elements of c.
Preconditions:
- k must be less than or equal to the size of c
- c must not be empty
If the preconditions are not met, an IllegalArgumentException is
thrown.
Parameters:
c - collection to be sampled
Parameters:
k - size of the sample random sample of k elements from c |
| nextSecureHexString | | String nextSecureHexString(int len)(Code) | | Generates a random string of hex characters from a secure random
sequence.
If cryptographic security is not required,
use nextHexString().
Preconditions:
len > 0 (otherwise an IllegalArgumentException
is thrown.)
Parameters:
len - length of return string the random hex string |
| nextSecureInt | | int nextSecureInt(int lower, int upper)(Code) | | Generates a uniformly distributed random integer between
lower and upper (endpoints included)
from a secure random sequence.
Sequences of integers generated using this method will be
cryptographically secure. If cryptographic security is not required,
nextInt should be used instead of this method.
Definition:
Secure Random Sequence
Preconditions:
lower < upper (otherwise an IllegalArgumentException
is thrown.)
Parameters:
lower - lower bound for generated integer
Parameters:
upper - upper bound for generated integer a random integer greater than or equal to lowerand less than or equal to upper. |
| nextSecureLong | | long nextSecureLong(long lower, long upper)(Code) | | Generates a random long integer between lower
and upper (endpoints included).
Sequences of long values generated using this method will be
cryptographically secure. If cryptographic security is not required,
nextLong should be used instead of this method.
Definition:
Secure Random Sequence
Preconditions:
lower < upper (otherwise an IllegalArgumentException
is thrown.)
Parameters:
lower - lower bound for generated integer
Parameters:
upper - upper bound for generated integer a long integer greater than or equal to lowerand less than or equal to upper. |
| nextUniform | | double nextUniform(double lower, double upper)(Code) | | Generates a uniformly distributed random value from the open interval
(lower,upper) (i.e., endpoints excluded).
Definition:
Uniform Distribution lower and
upper - lower are the
location and scale parameters, respectively.
Preconditions:
lower < upper (otherwise an IllegalArgumentException
is thrown.)
Parameters:
lower - lower endpoint of the interval of support
Parameters:
upper - upper endpoint of the interval of support uniformly distributed random value between lowerand upper (exclusive) |
|
|