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ObjectStatistics
public class Statistics
Holds some statistics about a series of sample values. Given a series of sample values s0, s1, s2, s3..., this class computes minimum, maximum, mean, root mean square and standard deviation. Statistics are computed on the fly; the sample values are never stored in memory.
An instance of Statistics
is initially empty (i.e. all statistical values are set
to NaN
). The statistics are updated every time an add(double)
method is invoked with a non-NaN value. A typical usage of this
class is:
double[] data = new double[1000]; // (Compute some data values here...) Statistics stats = new Statistics(); for (int i=0; i<data.length; i++) { stats.add(data[i]); } System.out.println(stats);
Nested Class Summary | |
---|---|
static class |
Statistics.Delta
Holds some statistics about a series of sample values and the difference between them. |
Constructor Summary | |
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Statistics()
Constructs an initially empty set of statistics. |
Method Summary | |
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void |
add(double sample)
Updates statistics for the specified sample. |
void |
add(long sample)
Updates statistics for the specified sample. |
void |
add(Statistics stats)
Updates statistics with all samples from the specified stats . |
Statistics |
clone()
Returns a clone of this statistics. |
int |
count()
Returns the number of samples, excluding NaN values. |
int |
countNaN()
Returns the number of NaN samples. |
boolean |
equals(Object obj)
Tests this statistics with the specified object for equality. |
int |
hashCode()
Returns a hash code value for this statistics. |
double |
maximum()
Returns the maximum sample value, or NaN if none. |
double |
mean()
Returns the mean value, or NaN if none. |
double |
minimum()
Returns the minimum sample value, or NaN if none. |
double |
range()
Returns the range of sample values. |
void |
reset()
Resets the statistics to their initial NaN values. |
double |
rms()
Returns the root mean square, or NaN if none. |
double |
standardDeviation(boolean allPopulation)
Retourne l'écart type des échantillons par rapport à la moyenne. |
String |
toString()
Returns a string representation of this statistics. |
String |
toString(Locale locale,
boolean tabulations)
Returns a localized string representation of this statistics. |
Methods inherited from class Object |
---|
finalize, getClass, notify, notifyAll, wait, wait, wait |
Constructor Detail |
---|
public Statistics()
Double.NaN
.
Method Detail |
---|
public void reset()
NaN
values.
This method reset this object state as if it was just created.
public void add(double sample)
add
method is usually invoked inside a for
loop.
sample
- The sample value. NaN
values are ignored.add(long)
,
add(Statistics)
public void add(long sample)
add
method is usually invoked inside a for
loop.
sample
- The sample value.add(double)
,
add(Statistics)
public void add(Statistics stats)
stats
. Invoking this
method is equivalent (except for rounding errors) to invoking add
for all samples that were added to stats
.
stats
- The statistics to be added to this
, or null
if none.public int countNaN()
NaN
samples. NaN
samples are
ignored in all other statitical computation. This method count them for information
purpose only.
public int count()
NaN
values.
public double minimum()
NaN
if none.
maximum()
public double maximum()
NaN
if none.
minimum()
public double range()
maximum
-
minimum
, except for rounding error. If no samples were added,
then returns NaN
.
minimum()
,
maximum()
public double mean()
NaN
if none.
public double rms()
NaN
if none.
public double standardDeviation(boolean allPopulation)
add(...)
se distribuent selon une
loi normale, alors l'écart type est la distance de part et d'autre de la moyenne
dans lequel se trouveraient environ 84% des données. Le tableau ci-dessous donne
le pourcentage approximatif des données que l'on trouve de part et d'autre de la
moyenne à des distances telles que 2 ou 3 fois l'écart-type.
0.5 | 69.1% |
1.0 | 84.2% |
1.5 | 93.3% |
2.0 | 97.7% |
3.0 | 99.9% |
allPopulation
- La valeur true
indique que les données fournies
aux différentes méthodes add(...)
représentent l'ensemble de
la polulation. La valeur false
indique que ces données ne
représentent qu'un échantillon de la population, ce qui est généralement le
cas. Si le nombre de données est élevé, alors les valeurs true
et false
donneront sensiblement les mêmes résultats.public Statistics clone()
clone
in class Object
Object.clone()
public boolean equals(Object obj)
equals
in class Object
public int hashCode()
hashCode
in class Object
public final String toString()
toString(Locale, boolean)
using the default locale and spaces
separator.
toString
in class Object
public String toString(Locale locale, boolean tabulations)
IfCompte: 8726 Minimum: 6.853 Maximum: 8.259 Moyenne: 7.421 RMS: 7.846 Écart-type: 6.489
tabulations
is true, then labels (e.g. "Minimum") and values
(e.g. "6.853") are separated by tabulations. Otherwise, they are separated
by spaces.
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