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public interface RelationalOperators
Method Summary | |
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Relation |
renameColumns(ColumnRenamer renamer)
Applies the rename operator to this relation. |
Relation |
select(Map attributeConditions)
Applies the selection operator to this relation, using equality conditions on a number of attributes as the selection expression. |
Method Detail |
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Relation select(Map attributeConditions)
Applies the selection operator to this relation, using equality conditions on a number of attributes as the selection expression. The new relation will contain only tuples whose attribute values are equal to the string values in the argument map.
Selection on attributes that don't exist in the relation are considered to be always false and will cause an empty relation.
attributeConditions
- A map from Attribute
s to Strings
Relation renameColumns(ColumnRenamer renamer)
Applies the rename operator to this relation.
Renames of attributes that don't exist in the relation are ignored.
renamer
- A map from original to replacement names
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