Class IntMean
- All Implemented Interfaces:
DoubleSupplier
,IntConsumer
,IntSupplier
,LongSupplier
,IntStatistic
,StatisticAccumulator<IntMean>
,StatisticResult
\[ \frac{1}{n} \sum_{i=1}^n x_i \]
where \( n \) is the number of samples.
- The result is
NaN
if no values are added.
This class uses an exact integer sum to compute the mean. Supports up to 263 (exclusive) observations. This implementation does not check for overflow of the count.
This class is designed to work with (though does not require) streams.
This implementation is not thread safe.
If multiple threads access an instance of this class concurrently,
and at least one of the threads invokes the accept
or
combine
method, it must be synchronized externally.
However, it is safe to use accept
and combine
as accumulator
and combiner
functions of
Collector
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.
- Since:
- 1.1
- See Also:
-
Field Summary
Fields -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionvoid
accept
(int value) Updates the state of the statistic to reflect the addition ofvalue
.Combines the state of theother
statistic into this one.(package private) static double
computeMean
(Int128 sum, long n) Compute the mean.static IntMean
create()
Creates an instance.double
Gets the mean of all input values.static IntMean
of
(int... values) Returns an instance populated using the inputvalues
.Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Methods inherited from interface java.util.function.IntConsumer
andThen
Methods inherited from interface org.apache.commons.statistics.descriptive.StatisticResult
getAsBigInteger, getAsInt, getAsLong
-
Field Details
-
SMALL_N
private static final long SMALL_NLimit for small sample size where the sum can exactly map to a double. This is conservatively set using 2^21 values of 2^31 (2^21 ~ 2 million).- See Also:
-
sum
Sum of the values. -
n
private long nCount of values that have been added.
-
-
Constructor Details
-
IntMean
private IntMean()Create an instance. -
IntMean
Create an instance.- Parameters:
sum
- Sum of the values.n
- Count of values that have been added.
-
-
Method Details
-
create
Creates an instance.The initial result is
NaN
.- Returns:
IntMean
instance.
-
of
Returns an instance populated using the inputvalues
.- Parameters:
values
- Values.- Returns:
IntMean
instance.
-
accept
public void accept(int value) Updates the state of the statistic to reflect the addition ofvalue
.- Specified by:
accept
in interfaceIntConsumer
- Parameters:
value
- Value.
-
getAsDouble
public double getAsDouble()Gets the mean of all input values.When no values have been added, the result is
NaN
.- Specified by:
getAsDouble
in interfaceDoubleSupplier
- Returns:
- mean of all values.
-
computeMean
Compute the mean.This is a helper method used in higher order moments.
- Parameters:
sum
- Sum of the values.n
- Count of the values.- Returns:
- the mean
-
combine
Description copied from interface:StatisticAccumulator
Combines the state of theother
statistic into this one.- Specified by:
combine
in interfaceStatisticAccumulator<IntMean>
- Parameters:
other
- Another statistic to be combined.- Returns:
this
instance after combiningother
.
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