public class LongMomentStatistics extends Object implements LongConsumer, IntConsumer
LongSummaryStatistics
class.
This class is designed to work with (though does not require) streams. For example, you can compute moments-statistics on a stream of longs with:
final LongStream stream = ...
final LongMomentStatistics statistics = stream.collect(
LongMomentStatistics::new,
LongMomentStatistics::accept,
LongMomentStatistics::combine
);
final Stream<SomeObject> stream = ...
final LongMomentStatistics statistics = stream
.collect(toLongMomentStatistics(v -> v.longValue()));
Implementation note:
This implementation is not thread safe. However, it is safe to use
toLongMomentStatistics(ToLongFunction)
on a parallel stream, because the parallel
implementation of Stream.collect()
provides the necessary partitioning, isolation, and merging of results for
safe and efficient parallel execution.
LongSummaryStatistics
,
LongMoments
,
Computing Higher-Order Moments OnlineConstructor and Description |
---|
LongMomentStatistics()
Create an empty moments object.
|
Modifier and Type | Method and Description |
---|---|
void |
accept(int value)
Records a new value into the moments information
|
void |
accept(long value)
Records a new value into the moments information
|
LongMomentStatistics |
combine(LongMomentStatistics other)
Combine two
LongMoments statistic objects. |
long |
getCount()
Returns the count of values recorded.
|
double |
getKurtosis()
Return the kurtosis of values recorded, or
Double.NaN if less
than four values have been recorded. |
long |
getMax()
Return the maximum value recorded, or
Long.MIN_VALUE if no
values have been recorded. |
double |
getMean()
Return the arithmetic mean of values recorded, or
Double.NaN if
no values have been recorded. |
long |
getMin()
Return the minimum value recorded, or
Long.MAX_VALUE if no
values have been recorded. |
double |
getSkewness()
Return the skewness of values recorded, or
Double.NaN if less
than two values have been recorded. |
long |
getSum()
Return the sum of values recorded, or zero if no values have been
recorded.
|
double |
getVariance()
Return the variance of values recorded, or
Double.NaN if no
values have been recorded. |
boolean |
sameState(LongMomentStatistics other)
Compares the state of two
LongMomentStatistics objects. |
LongMoments |
toLongMoments()
Return a
LongMoments object from the current statistics, |
static <T> Collector<T,?,LongMomentStatistics> |
toLongMomentStatistics(ToLongFunction<? super T> mapper)
Return a
Collector which applies an long-producing mapping
function to each input element, and returns moments-statistics for the
resulting values. |
String |
toString() |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
andThen
andThen
public LongMomentStatistics()
public void accept(long value)
accept
in interface LongConsumer
value
- the input value
public void accept(int value)
accept
in interface IntConsumer
value
- the input value
public LongMomentStatistics combine(LongMomentStatistics other)
LongMoments
statistic objects.other
- the other LongMoments
statistics to combine with
this
one.this
statistics objectNullPointerException
- if the other statistical summary
is null
.public long getMin()
Long.MAX_VALUE
if no
values have been recorded.Long.MAX_VALUE
if nonepublic long getMax()
Long.MIN_VALUE
if no
values have been recorded.Long.MIN_VALUE
if nonepublic long getSum()
public boolean sameState(LongMomentStatistics other)
LongMomentStatistics
objects. This is
a replacement for the Object.equals(Object)
which is not advisable to
implement for this mutable object. If two object have the same state, it
has still the same state when updated with the same value.
final LongMomentStatistics lms1 = ...;
final LongMomentStatistics lms2 = ...;
if (lms1.sameState(lms2)) {
final long value = random.nextInt(1_000_000);
lms1.accept(value);
lms2.accept(value);
assert lms1.sameState(lms2);
assert lms2.sameState(lms1);
assert lms1.sameState(lms1);
}
other
- the other object for the testtrue
the this
and the other
objects have
the same state, false
otherwisepublic LongMoments toLongMoments()
LongMoments
object from the current statistics,LongMoments
object from the current statisticspublic static <T> Collector<T,?,LongMomentStatistics> toLongMomentStatistics(ToLongFunction<? super T> mapper)
Collector
which applies an long-producing mapping
function to each input element, and returns moments-statistics for the
resulting values.
final Stream<SomeObject> stream = ...
final LongMomentStatistics statistics = stream
.collect(toLongMomentStatistics(v -> v.longValue()));
T
- the type of the input elementsmapper
- a mapping function to apply to each elementCollector
implementing the moments-statistics reductionNullPointerException
- if the given mapper
is
null
public long getCount()
public double getMean()
Double.NaN
if
no values have been recorded.public double getVariance()
Double.NaN
if no
values have been recorded.NaN
if nonepublic double getSkewness()
Double.NaN
if less
than two values have been recorded.NaN
if less than two values
have been recordedpublic double getKurtosis()
Double.NaN
if less
than four values have been recorded.NaN
if less than four values
have been recorded© 2007-2017 Franz Wilhelmstötter (2017-08-22 19:30)