uk.ac.starlink.ttools.filter
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
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
SortHeadFilter
public SortHeadFilter()
getDescriptionLines
protected String[] getDescriptionLines()
- Specified by:
getDescriptionLines
in class BasicFilter
createStep
public ProcessingStep createStep(Iterator 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.
If its usageFrament
is blank, it will be filled in
later using this mode's usage text.
- Parameters:
argIt
- iterator over command-line arguments positioned
at the first one
- Throws:
ArgException
Copyright © 2009 Central Laboratory of the Research Councils. All Rights Reserved.