Package uk.ac.starlink.ttools.task
Class CombinedColumn
java.lang.Object
uk.ac.starlink.ttools.task.CombinedColumn
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 -
Method Summary
Modifier and TypeMethodDescriptionstatic StringMultiParameter
createCombinedColumnsParameter
(String name, CombinerParameter dfltCombinerParam) Creates a parameter for specifying aggregate columns.Returns the aggregation method.Returns the expression to be aggregated.getName()
Returns the output column name.static CombinedColumn
parseSpecification
(uk.ac.starlink.task.Environment env, String txt, uk.ac.starlink.task.Parameter<?> txtParam, CombinerParameter combinerParam) Parses an input expression to a CombinedColumn value.
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Constructor Details
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CombinedColumn
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 Details
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getExpression
Returns the expression to be aggregated.- Returns:
- input column name or expression, not null
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getCombiner
Returns the aggregation method.- Returns:
- aggregation method, or null to indicate default
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getName
Returns the output column name.- Returns:
- output name, or null to indicate default
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parseSpecification
public static CombinedColumn parseSpecification(uk.ac.starlink.task.Environment env, String txt, uk.ac.starlink.task.Parameter<?> txtParam, CombinerParameter combinerParam) throws uk.ac.starlink.task.ParameterValueException Parses an input expression to a CombinedColumn value.- Parameters:
env
- execution environmenttxt
- 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(String name, CombinerParameter 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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