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java.lang.Objectcern.colt.PersistentObject
cern.jet.stat.tfloat.quantile.FloatEquiDepthHistogram
public class FloatEquiDepthHistogram
Read-only equi-depth histogram for selectivity estimation. Assume you have collected statistics over a data set, among them a one-dimensional equi-depth histogram (quantiles). Then an applications or DBMS might want to estimate the selectivity of some range query [from,to], i.e. the percentage of data set elements contained in the query range. This class does not collect equi-depth histograms but only space efficiently stores already produced histograms and provides operations for selectivity estimation. Uses linear interpolation.
This class stores a list l of float values for which holds:
Constructor Summary | |
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FloatEquiDepthHistogram(float[] quantileElements)
Constructs an equi-depth histogram with the given quantile elements. |
Method Summary | |
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int |
binOfElement(float element)
Returns the bin index of the given element. |
int |
bins()
Returns the number of bins. |
float |
endOfBin(int binIndex)
Returns the end of the range associated with the given bin. |
double |
percentFromTo(float from,
float to)
Returns the percentage of elements in the range (from,to]. |
double |
phi(float element)
Returns how many percent of the elements contained in the receiver are <= element. |
int |
size()
Deprecated. Deprecated. Returns the number of bin boundaries. |
float |
startOfBin(int binIndex)
Returns the start of the range associated with the given bin. |
static void |
test(float element)
Not yet commented. |
Methods inherited from class cern.colt.PersistentObject |
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clone |
Methods inherited from class java.lang.Object |
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equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public FloatEquiDepthHistogram(float[] quantileElements)
Method Detail |
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public int binOfElement(float element)
element
- the element to search for.
IllegalArgumentException
- if the element is not contained in any bin.public int bins()
public float endOfBin(int binIndex)
ArrayIndexOutOfBoundsException
- if binIndex < 0 || binIndex >= bins().public double percentFromTo(float from, float to)
from
- the start point (exclusive).to
- the end point (inclusive).
public double phi(float element)
element
- the element to search for.
@Deprecated public int size()
public float startOfBin(int binIndex)
ArrayIndexOutOfBoundsException
- if binIndex < 0 || binIndex >= bins().public static void test(float element)
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