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java.lang.Objectuk.ac.starlink.ttools.example.AllWiseTableBuilder
public class AllWiseTableBuilder
TableBuilder implementation for the ASCII files comprising the AllWise data release. At time of writing these files are available from http://irsadist.ipac.caltech.edu/wise-allwise/. The files are formatted as pipe-separated ASCII, and optionally compressed. Note that reading seems to be considerably faster for the gzip than for the bzip2 form of the input files (though the gzip ones are a bit bigger).
For FITS output (though not colfits) two passes through the input ASCII file are required, the first one (much faster) just to count the rows. There are therefore two variants of this input handler, one which does a row count and one which does not. If the row count is known, it would be possible to adapt this handler so you tell it the row count up front and only one pass is required.
Nested Class Summary | |
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static class |
AllWiseTableBuilder.Count
Input handler which reads AllWise ASCII files and does count the rows first. |
static class |
AllWiseTableBuilder.NoCount
Input handler which reads AllWise ASCII files and does not count the rows first. |
Constructor Summary | |
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AllWiseTableBuilder()
Default mode constructor. |
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AllWiseTableBuilder(String name,
boolean preCount)
Configurable constructor. |
Method Summary | |
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boolean |
canImport(DataFlavor flavor)
Indicates whether this builder is able to turn a resource of media type indicated by flavor into a table. |
static long |
countLines(DataSource datsrc)
Counts the lines in the ASCII file at the given location. |
String |
getFormatName()
Returns the name of the format which can be read by this handler. |
StarTable |
makeStarTable(DataSource datsrc,
boolean wantRandom,
StoragePolicy storagePolicy)
Constructs a StarTable based on a given DataSource. |
void |
streamStarTable(InputStream in,
TableSink sink,
String pos)
Reads a table from an input stream and writes it a row at a time to a sink. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public AllWiseTableBuilder()
public AllWiseTableBuilder(String name, boolean preCount)
name
- handler namepreCount
- true to return a table that knows its row countMethod Detail |
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public boolean canImport(DataFlavor flavor)
TableBuilder
TableBuilder.streamStarTable(java.io.InputStream, uk.ac.starlink.table.TableSink, java.lang.String)
method stands a reasonable chance of
successfully constructing a StarTable from a
DataSource whose input stream is described by the
DataFlavor
flavor.
It will typically make this determination based on the flavor's
MIME type.
This method should only return true if the flavor looks like it is targeted at this builder; for instance a builder which uses a text-based format should return false for a flavor which indicates a MIME type of text/plain.
This method is used in supporting drag and drop functionality
(see StarTableFactory.canImport(java.awt.datatransfer.DataFlavor[])
).
canImport
in interface TableBuilder
flavor
- the DataFlavor whose suitability as stream input
is to be assessed
public String getFormatName()
TableBuilder
getFormatName
in interface TableBuilder
public StarTable makeStarTable(DataSource datsrc, boolean wantRandom, StoragePolicy storagePolicy) throws IOException
TableBuilder
StarTable
based on a given DataSource.
If the source is not recognised or this builder does not know
how to construct a table from it, then a
TableFormatException
should be thrown.
If this builder thinks it should be able to handle the source
but an error occurs during processing, an IOException
can be thrown.
The wantRandom parameter is used to indicate whether, ideally, a random-access table should be returned. There is no requirement for the builder to honour this request, but if it knows how to make both random and non-random tables, it can use this flag to decide which to return.
Note: the presence of the wantRandom
parameter is somewhat misleading. TableBuilder implementations
usually should, and do, ignore it (it would be removed from the
interface if it were not for backward compatibility issues).
Regardless of the value of this parameter, implementations should
return a random-access table only if it is easy for them to do so;
in particular they should not use the supplied
storagePolicy
, or any other resource-expensive measure,
to randomise a sequential table just because the
wantRandom
parameter is true.
makeStarTable
in interface TableBuilder
datsrc
- the DataSource containing the table resourcewantRandom
- whether, preferentially, a random access table
should be returnedstoragePolicy
- a StoragePolicy object which may be used to
supply scratch storage if the builder needs it
TableFormatException
- if the table is not of a kind that
can be handled by this handler
IOException
- if an unexpected I/O error occurs during processingpublic void streamStarTable(InputStream in, TableSink sink, String pos)
TableBuilder
TableFormatException
.
The input stream should be prepared for use prior to calling this method, so implementations should not in general attempt to decompress or buffer istrm.
streamStarTable
in interface TableBuilder
in
- input stream containing table datasink
- destination of the tablepos
- position identifier describing the location of the
table within the stream;
see DataSource.getPosition()
(may be null)public static long countLines(DataSource datsrc) throws IOException
datsrc
- data source
IOException
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