Package uk.ac.starlink.ttools.task
Class CombinedColumn
- java.lang.Object
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- uk.ac.starlink.ttools.task.CombinedColumn
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public class CombinedColumn extends java.lang.Object
Describes an output column formed by aggregation of values from an input expression.- Since:
- 21 Dec 2021
- Author:
- Mark Taylor
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Constructor Summary
Constructors Constructor Description CombinedColumn(java.lang.String expr, Combiner combiner, java.lang.String name)
Constructor.
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description static StringMultiParameter
createCombinedColumnsParameter(java.lang.String name, uk.ac.starlink.task.Parameter<Combiner> dfltCombinerParam)
Creates a parameter for specifying aggregate columns.Combiner
getCombiner()
Returns the aggregation method.java.lang.String
getExpression()
Returns the expression to be aggregated.java.lang.String
getName()
Returns the output column name.static CombinedColumn
parseSpecification(java.lang.String txt, uk.ac.starlink.task.Parameter<?> txtParam, uk.ac.starlink.task.ChoiceParameter<Combiner> combinerParam)
Parses an input expression to a CombinedColumn value.
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Constructor Detail
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CombinedColumn
public CombinedColumn(java.lang.String expr, Combiner combiner, java.lang.String name)
Constructor.- Parameters:
expr
- expression to be aggregatedcombiner
- aggregation method, may be null to indicate defaultname
- name of output column, may be null to indicate default
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Method Detail
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getExpression
public java.lang.String getExpression()
Returns the expression to be aggregated.- Returns:
- input column name or expression, not null
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getCombiner
public Combiner getCombiner()
Returns the aggregation method.- Returns:
- aggregation method, or null to indicate default
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getName
public java.lang.String getName()
Returns the output column name.- Returns:
- output name, or null to indicate default
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parseSpecification
public static CombinedColumn parseSpecification(java.lang.String txt, uk.ac.starlink.task.Parameter<?> txtParam, uk.ac.starlink.task.ChoiceParameter<Combiner> combinerParam) throws uk.ac.starlink.task.ParameterValueException
Parses an input expression to a CombinedColumn value.- Parameters:
txt
- input expressiontxtParam
- parameter supplying input value, used for reference in thrown exceptionscombinerParam
- parameter supplying combiner values, used to decode combiner specifications- Throws:
uk.ac.starlink.task.ParameterValueException
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createCombinedColumnsParameter
public static StringMultiParameter createCombinedColumnsParameter(java.lang.String name, uk.ac.starlink.task.Parameter<Combiner> dfltCombinerParam)
Creates a parameter for specifying aggregate columns. The parameter return value is an array of strings, each of which can be parsed using theparseSpecification
method.- Parameters:
name
- parameter namedfltCombinerParam
- parameter used for specifying default aggregation method, used in documentation
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