org.das2.qds.ops

Class CoerceUtil

java.lang.Object

org.das2.qds.ops.CoerceUtil

public class CoerceUtil
extends java.lang.Object

Utility class for reconciling the geometries of two datasets. For example, a rank 1 dataset's values can be repeated to make it rank 2. TODO: dataset geometry is increased by keeping a reference to a dataset with the target geometry. This might result in keeping data in memory that would otherwise be released, so a future implementation of this should probably use a non-qube dataset to store each index's length:

 public int length() {
    return lengths.length()
 }
 public int length(int i0) {
    return lengths.value(i0);
 }

Constructor Summary

Constructors

Constructor and Description
CoerceUtil()

Method Summary

Modifier and Type	Method and Description
static WritableDataSet	coerce(QDataSet ds1, QDataSet ds2, boolean createResult, QDataSet[] operands) increase rank of datasets so that element-wise operations can be performed.
static boolean	equalGeom(QDataSet ds1, QDataSet ds2) returns true if two datasets have the same number of elements in each dimension.
static QDataSet	increaseRank0(QDataSet ds, QDataSet ds2) increase the rank of a rank zero dataset by adding join dimensions that repeat the lower rank elements.
static QDataSet	increaseRank1(QDataSet ds, QDataSet ds2) increase the rank of a rank one dataset by adding join dimensions that repeat the lower rank elements.
static QDataSet	increaseRank2(QDataSet ds, QDataSet ds2) increase the rank of a rank two dataset by adding join dimensions that repeat the lower rank elements.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CoerceUtil

public CoerceUtil()

Method Detail

equalGeom

public static boolean equalGeom(QDataSet ds1,
                                QDataSet ds2)

returns true if two datasets have the same number of elements in each dimension.

Parameters:

ds1 -

ds2 -

Returns:

returns true if two datasets have the same number of elements in each dimension.

coerce

public static WritableDataSet coerce(QDataSet ds1,
                                     QDataSet ds2,
                                     boolean createResult,
                                     QDataSet[] operands)

increase rank of datasets so that element-wise operations can be performed. For example, if a rank 1 and a rank 2 dataset are to be combined and both have equal dim 0 length, then the rank 1 is promoted to rank 2 by repeating its values. This implements the rule that dimensions in QDataSet have nested context. The second dimension elements are to be understood in the context of the first dimension element. (Except for qubes, where the order is arbitrary.)

Parameters:

ds1 - the first operand

ds2 - the second operand

createResult - if true, then a dataset is created where the result can be installed.

operands - the array in which the promoted operands are inserted.

Returns:

an empty dataset where the results can be inserted, or null if createResult is false.

increaseRank0

public static QDataSet increaseRank0(QDataSet ds,
                                     QDataSet ds2)

increase the rank of a rank zero dataset by adding join dimensions that repeat the lower rank elements.

Parameters:

ds - a rank 0 dataset

ds2 - dataset to provide rank and lengths.

Returns:

a dataset with the same geometry as ds2.

increaseRank1

public static QDataSet increaseRank1(QDataSet ds,
                                     QDataSet ds2)

increase the rank of a rank one dataset by adding join dimensions that repeat the lower rank elements.

Parameters:

ds - a rank 1 dataset to provide values and properties

ds2 - dataset to provide rank and lengths.

Returns:

a dataset with the same geometry as ds2.

increaseRank2

public static QDataSet increaseRank2(QDataSet ds,
                                     QDataSet ds2)

increase the rank of a rank two dataset by adding join dimensions that repeat the lower rank elements.

Parameters:

ds - a rank 2 dataset to provide values and properties

ds2 - dataset to provide rank and lengths.

Returns:

a dataset with the same geometry as ds2.