Class SortHeadFilter

java.lang.Object
uk.ac.starlink.ttools.filter.BasicFilter
uk.ac.starlink.ttools.filter.SortHeadFilter
All Implemented Interfaces:
ProcessingFilter

public class SortHeadFilter extends BasicFilter
Filter for returning the first (or last) few rows of a sorted table. This is functionally equivalent to using sort followed by head, but the algorithm is different (a complete sort is not necessary), so this way will usually be faster.
Since:
12 Oct 2005
Author:
Mark Taylor
  • Constructor Details

    • SortHeadFilter

      public SortHeadFilter()
  • Method Details

    • getDescriptionLines

      protected String[] getDescriptionLines()
      Specified by:
      getDescriptionLines in class BasicFilter
    • createStep

      public ProcessingStep createStep(Iterator<String> argIt) throws ArgException
      Description copied from interface: ProcessingFilter
      Creates a new ProcessingStep based on a sequence of command-line arguments. The argIt argument is an iterator over the command-line arguments positioned just before any arguments intended for this filter. If legal, any that can be comprehended by this filter should be read (iterated over) and removed, and a ProcessingStep should accordingly be returned. In the case of a successful return, it is essential that no arguments other than the ones intended for this filter are read from the iterator.

      If the argument list is badly-formed as far as this filter is concerned, an ArgException should be thrown.

      Parameters:
      argIt - iterator over command-line arguments positioned at the first one
      Throws:
      ArgException