Class Median
For values of length n
, let k = n / 2
:
- The result is
NaN
ifn = 0
. - The result is
values[k]
ifn
is odd. - The result is
(values[k - 1] + values[k]) / 2
ifn
is even.
This implementation respects the ordering imposed by
Double.compare(double, double)
for NaN
values. If a NaN
occurs
in the selected positions in the fully sorted values then the result is NaN
.
The NaNPolicy
can be used to change the behaviour on NaN
values.
Instances of this class are immutable and thread-safe.
- Since:
- 1.1
- See Also:
-
Field Summary
FieldsModifier and TypeFieldDescriptionprivate final boolean
Flag to indicate if the data should be copied.private static final Median
Default instance.private final NaNPolicy
NaN policy for floating point data.private final NaNTransformer
Transformer for NaN data. -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptiondouble
evaluate
(double[] values) Evaluate the median.double
evaluate
(int[] values) Evaluate the median.Return an instance with the configuredNaNPolicy
.withCopy
(boolean v) Return an instance with the configured copy behaviour.static Median
Return a new instance with the default options.
-
Field Details
-
DEFAULT
Default instance. -
copy
private final boolean copyFlag to indicate if the data should be copied. -
nanPolicy
NaN policy for floating point data. -
nanTransformer
Transformer for NaN data.
-
-
Constructor Details
-
Median
- Parameters:
copy
- Flag to indicate if the data should be copied.nanPolicy
- NaN policy.
-
-
Method Details
-
withDefaults
Return a new instance with the default options.Note: The default options configure for processing in-place and including
NaN
values in the data. This is the most efficient mode and has the smallest memory consumption.- Returns:
- the median implementation
- See Also:
-
withCopy
Return an instance with the configured copy behaviour. Iffalse
then the input array will be modified by the call to evaluate the median; otherwise the computation uses a copy of the data.- Parameters:
v
- Value.- Returns:
- an instance
-
with
Return an instance with the configuredNaNPolicy
.Note: This implementation respects the ordering imposed by
Double.compare(double, double)
forNaN
values:NaN
is considered greater than all other values, and allNaN
values are equal. TheNaNPolicy
changes the computation of the statistic in the presence ofNaN
values.NaNPolicy.INCLUDE
:NaN
values are moved to the end of the data; the size of the data includes theNaN
values and the median will beNaN
if any value used for median interpolation isNaN
.NaNPolicy.EXCLUDE
:NaN
values are moved to the end of the data; the size of the data excludes theNaN
values and the median will never beNaN
for non-zero size. If all data areNaN
then the size is zero and the result isNaN
.NaNPolicy.ERROR
: An exception is raised if the data containsNaN
values.
Note that the result is identical for all policies if no
NaN
values are present.- Parameters:
v
- Value.- Returns:
- an instance
-
evaluate
public double evaluate(double[] values) Evaluate the median.Note: This method may partially sort the input values if not configured to
copy
the input data.- Parameters:
values
- Values.- Returns:
- the median
-
evaluate
public double evaluate(int[] values) Evaluate the median.Note: This method may partially sort the input values if not configured to
copy
the input data.- Parameters:
values
- Values.- Returns:
- the median
-