Package com.pervasivecode.utils.stats.histogram

Class FunctionBasedBucketSelector<T>

java.lang.Object

com.pervasivecode.utils.stats.histogram.FunctionBasedBucketSelector<T>

Type Parameters:

T - The type of upper bound value used by this BucketSelector.

All Implemented Interfaces:

BucketingSystem<T>, BucketSelector<T>

public final class FunctionBasedBucketSelector<T>
extends Object
implements BucketSelector<T>

A BucketSelector based on a pair of Functions, one of which converts values into bucket indices, the other of which converts bucket indices into upper-bound values.

See Also:

BucketingSystem

Constructor Summary

Constructors

Constructor	Description
FunctionBasedBucketSelector(Function<T,Integer> valueToBucketIndexFunction, Function<Integer,T> bucketIndexToUpperBoundFunction, int numBuckets)	Create a BucketSelector using a Function that converts an upper-bound value into a bucket index, and another Function that converts a bucket index into an upper-bound value.

Method Summary

Modifier and Type	Method	Description
int	bucketIndexFor(T value)	Determine the index of the bucket that a specified value should be counted in.
T	bucketUpperBound(int index)	Get the upper-bound value of the specified bucket.
int	numBuckets()	Get the total number of buckets.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

FunctionBasedBucketSelector

public FunctionBasedBucketSelector(Function<T,Integer> valueToBucketIndexFunction,
                                   Function<Integer,T> bucketIndexToUpperBoundFunction,
                                   int numBuckets)

Create a BucketSelector using a Function that converts an upper-bound value into a bucket index, and another Function that converts a bucket index into an upper-bound value.

Note: neither function will have to handle null values.

Parameters:

valueToBucketIndexFunction - A function that selects a bucket index for a given value of type T.

bucketIndexToUpperBoundFunction - A function that returns the upper-bound value for a given bucket index.

numBuckets - The total number of buckets including the highest, unbounded bucket.

Method Detail

numBuckets

public int numBuckets()

Description copied from interface: BucketingSystem

Get the total number of buckets. This will not be smaller than 1.

Specified by:

numBuckets in interface BucketingSystem<T>

Returns:

The number of buckets.

bucketUpperBound

public T bucketUpperBound(int index)

Description copied from interface: BucketingSystem

Get the upper-bound value of the specified bucket.

The first bucket has an index of 0. The last bucket has no upper bound, so passing the last index value in index is not allowed and will result in an IllegalArgumentException being thrown. In other words, if there are 10 buckets in a given instance, there are only 9 upper bound values, so the valid index values are 0 through 8 inclusive.

A BucketingSystem with only one bucket is valid (all values fall in that bucket), but would have no upper bound values, so this method would always throw an IllegalArgumentException (for index value 0) or an IndexOutOfBoundsException (for all other values of index).

Specified by:

bucketUpperBound in interface BucketingSystem<T>

Parameters:

index - The bucket index to examine. This must be a value from zero through the next-to-last bucket index.

Returns:

The upper bound value of the specified bucket. This will not be null.

bucketIndexFor

public int bucketIndexFor(T value)

Description copied from interface: BucketSelector

Determine the index of the bucket that a specified value should be counted in.

Specified by:

bucketIndexFor in interface BucketSelector<T>

Parameters:

value - The value to compare to bucket upper bounds values when identifying the appropriate bucket.

Returns:

The bucket index for the specified value.