nom.tam.fits

Class Fits

java.lang.Object

nom.tam.fits.Fits

public class Fits
extends Object

This class provides access to routines to allow users to read and write FITS files.

Description of the Package

This FITS package attempts to make using FITS files easy, but does not do exhaustive error checking. Users should not assume that just because a FITS file can be read and written that it is necessarily legal FITS.

• The Fits class provides capabilities to read and write data at the HDU level, and to add and delete HDU's from the current Fits object. A large number of constructors are provided which allow users to associate the Fits object with some form of external data. This external data may be in a compressed format.
• The HDU class is a factory class which is used to create HDUs. HDU's can be of a number of types derived from the abstract class BasicHDU. The hierarchy of HDUs is:
  • BasicHDU
    • ImageHDU
    • RandomGroupsHDU
    • TableHDU
      • BinaryTableHDU
      • AsciiTableHDU
• The Header class provides many functions to add, delete and read header keywords in a variety of formats.
• The HeaderCard class provides access to the structure of a FITS header card.
• The Data class is an abstract class which provides the basic methods for reading and writing FITS data. Users will likely only be interested in the getData method which returns that actual FITS data.
• The TableHDU class provides a large number of methods to access and modify information in tables.
• The Column class combines the Header information and Data corresponding to a given column.

Copyright: Thomas McGlynn 1997-1999. This code may be used for any purpose, non-commercial or commercial so long as this copyright notice is retained in the source code or included in or referred to in any derived software.

Version:

0.96a October 10, 2000

Constructor Summary

Constructors

Constructor and Description
Fits() Create an empty Fits object which is not associated with an input stream.
Fits(File myFile) Associate FITS object with an uncompressed File
Fits(File myFile, boolean compressed) Associate the Fits object with a File
Fits(InputStream str) Create a Fits object associated with the given uncompressed data stream.
Fits(InputStream str, boolean compressed) Create a Fits object associated with a possibly compressed data stream.
Fits(String filename) Associate the FITS object with a file or URL.
Fits(URL myURL) Associate the FITS object with a given uncompressed URL
Fits(URL myURL, boolean compressed) Associate the FITS object with a given URL

Method Summary

Modifier and Type	Method and Description
void	addHDU(BasicHDU myHDU) Add an HDU to the Fits object.
int	currentSize() Deprecated. See getNumberOfHDUs()
void	deleteHDU(int n) Delete an HDU from the HDU list.
protected void	fileInit(File myFile, boolean compressed) Get a stream from the file and then use the stream initialization.
BasicHDU	getHDU(int n) Return the n'th HDU.
int	getNumberOfHDUs() Get the current number of HDUs in the Fits object.
ArrayDataInput	getStream() Get the data stream used for the Fits Data.
void	insertHDU(BasicHDU myHDU, int n) Insert a FITS object into the list of HDUs.
static BasicHDU	makeHDU(Data datum) Create an HDU from the given Data.
static BasicHDU	makeHDU(Header h) Create an HDU from the given header.
static BasicHDU	makeHDU(Object o) Create an HDU from the given data kernel.
protected void	randomInit(String filename) Initialize using buffered random access
BasicHDU[]	read() Return all HDUs for the Fits object.
void	read(InputStream is) Read a FITS file from an InputStream object.
BasicHDU	readHDU() Read the next HDU on the default input stream.
void	setStream(ArrayDataInput stream) Set the data stream to be used for future input.
int	size() Deprecated. The meaning of size of ambiguous. Use
void	skipHDU() Skip the next HDU on the default input stream.
void	skipHDU(int n) Skip HDUs on the associate input stream.
protected void	streamInit(InputStream str, boolean compressed, boolean seekable) Do the stream initialization.
static String	version() Indicate the version of these classes
void	write(DataOutput os) Write a Fits Object to an external Stream.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Fits

public Fits()

Create an empty Fits object which is not associated with an input stream.

Fits

public Fits(InputStream str)
     throws FitsException

Create a Fits object associated with the given uncompressed data stream.

Parameters:

str - The data stream.

Throws:

FitsException

Fits

public Fits(InputStream str,
            boolean compressed)
     throws FitsException

Create a Fits object associated with a possibly compressed data stream.

Parameters:

str - The data stream.

compressed - Is the stream compressed?

Throws:

FitsException

Fits

public Fits(File myFile)
     throws FitsException

Associate FITS object with an uncompressed File

Parameters:

myFile - The File object.

Throws:

FitsException

Fits

public Fits(File myFile,
            boolean compressed)
     throws FitsException

Associate the Fits object with a File

Parameters:

myFile - The File object.

compressed - Is the data compressed?

Throws:

FitsException

Fits

public Fits(String filename)
     throws FitsException

Associate the FITS object with a file or URL. The string is assumed to be a URL if it begins with http: otherwise it is treated as a file name. If the string ends in .gz it is assumed that the data is in a compressed format. All string comparisons are case insensitive.

Parameters:

filename - The name of the file or URL to be processed.

Throws:

FitsException - Thrown if unable to find or open a file or URL from the string given.

Fits

public Fits(URL myURL)
     throws FitsException

Associate the FITS object with a given uncompressed URL

Parameters:

myURL - The URL to be associated with the FITS file.

Throws:

FitsException - Thrown if unable to use the specified URL.

Fits

public Fits(URL myURL,
            boolean compressed)
     throws FitsException

Associate the FITS object with a given URL

Parameters:

myURL - The URL to be associated with the FITS file.

compressed - Is the data compressed?

Throws:

FitsException - Thrown if unable to find or open a file or URL from the string given.

Method Detail

version

public static String version()

Indicate the version of these classes

streamInit

protected void streamInit(InputStream str,
                          boolean compressed,
                          boolean seekable)
                   throws FitsException

Do the stream initialization.

Parameters:

str - The input stream.

compressed - Is this data compressed? If so, then the GZIPInputStream class will be used to inflate it.

Throws:

FitsException

randomInit

protected void randomInit(String filename)
                   throws FitsException

Initialize using buffered random access

Throws:

FitsException

fileInit

protected void fileInit(File myFile,
                        boolean compressed)
                 throws FitsException

Get a stream from the file and then use the stream initialization.

Parameters:

myFile - The File to be associated.

compressed - Is the data compressed?

Throws:

FitsException

read

public BasicHDU[] read()
                throws FitsException

Return all HDUs for the Fits object. If the FITS file is associated with an external stream make sure that we have exhausted the stream.

Returns:

an array of all HDUs in the Fits object. Returns null if there are no HDUs associated with this object.

Throws:

FitsException

readHDU

public BasicHDU readHDU()
                 throws FitsException,
                        IOException

Read the next HDU on the default input stream.

Returns:

The HDU read, or null if an EOF was detected. Note that null is only returned when the EOF is detected immediately at the beginning of reading the HDU.

Throws:

FitsException

IOException

skipHDU

public void skipHDU(int n)
             throws FitsException,
                    IOException

Skip HDUs on the associate input stream.

Parameters:

n - The number of HDUs to be skipped.

Throws:

FitsException

IOException

skipHDU

public void skipHDU()
             throws FitsException,
                    IOException

Skip the next HDU on the default input stream.

Throws:

FitsException

IOException

getHDU

public BasicHDU getHDU(int n)
                throws FitsException,
                       IOException

Return the n'th HDU. If the HDU is already read simply return a pointer to the cached data. Otherwise read the associated stream until the n'th HDU is read.

Parameters:

n - The index of the HDU to be read. The primary HDU is index 0.

Returns:

The n'th HDU or null if it could not be found.

Throws:

FitsException

IOException

size

public int size()
         throws FitsException

Deprecated. The meaning of size of ambiguous. Use

Return the number of HDUs in the Fits object. If the FITS file is associated with an external stream make sure that we have exhausted the stream.

Returns:

number of HDUs.

Throws:

FitsException

addHDU

public void addHDU(BasicHDU myHDU)
            throws FitsException

Add an HDU to the Fits object. Users may intermix calls to functions which read HDUs from an associated input stream with the addHDU and insertHDU calls, but should be careful to understand the consequences.

Parameters:

myHDU - The HDU to be added to the end of the FITS object.

Throws:

FitsException

insertHDU

public void insertHDU(BasicHDU myHDU,
                      int n)
               throws FitsException

Insert a FITS object into the list of HDUs.

Parameters:

myHDU - The HDU to be inserted into the list of HDUs.

n - The location at which the HDU is to be inserted.

Throws:

FitsException

deleteHDU

public void deleteHDU(int n)
               throws FitsException

Delete an HDU from the HDU list.

Parameters:

n - The index of the HDU to be deleted. If n is 0 and there is more than one HDU present, then the next HDU will be converted from an image to primary HDU if possible. If not a dummy header HDU will then be inserted.

Throws:

FitsException

write

public void write(DataOutput os)
           throws FitsException

Write a Fits Object to an external Stream.

Parameters:

dos - A DataOutput stream.

Throws:

FitsException

read

public void read(InputStream is)
          throws FitsException,
                 IOException

Read a FITS file from an InputStream object.

Parameters:

is - The InputStream stream whence the FITS information is found.

Throws:

FitsException

IOException

currentSize

public int currentSize()

Deprecated. See getNumberOfHDUs()

Get the current number of HDUs in the Fits object.

Returns:

The number of HDU's in the object.

getNumberOfHDUs

public int getNumberOfHDUs()

Get the current number of HDUs in the Fits object.

Returns:

The number of HDU's in the object.

getStream

public ArrayDataInput getStream()

Get the data stream used for the Fits Data.

Returns:

The associated data stream. Users may wish to call this function after opening a Fits object when they wish detailed control for writing some part of the FITS file.

setStream

public void setStream(ArrayDataInput stream)

Set the data stream to be used for future input.

Parameters:

stream - The data stream to be used.

makeHDU

public static BasicHDU makeHDU(Header h)
                        throws FitsException

Create an HDU from the given header.

Parameters:

h - The header which describes the FITS extension

Throws:

FitsException

makeHDU

public static BasicHDU makeHDU(Object o)
                        throws FitsException

Create an HDU from the given data kernel.

Parameters:

o - The data to be described in this HDU.

Throws:

FitsException

makeHDU

public static BasicHDU makeHDU(Data datum)
                        throws FitsException

Create an HDU from the given Data.

Parameters:

datum - The data to be described in this HDU.

Throws:

FitsException