pro writefits, filename, data, header, heap, Append = Append, $ compress = compress, CheckSum = checksum, NaNValue = NaNvalue ;+ ; NAME: ; WRITEFITS ; PURPOSE: ; Write IDL array and header variables to a disk FITS file. ; ; EXPLANATION: ; A minimal FITS header is created if not supplied. ; WRITEFITS works for all types of FITS files except random groups ; ; CALLING SEQUENCE: ; WRITEFITS, filename, data [, header, /APPEND, /COMPRESS, /CHECKSUM] ; ; INPUTS: ; FILENAME = String containing the name of the file to be written. ; ; DATA = Image array to be written to FITS file. If DATA is ; undefined or a scalar, then only the FITS header (which ; must have NAXIS = 0) will be written to disk ; ; OPTIONAL INPUT: ; HEADER = String array containing the header for the FITS file. ; If variable HEADER is not given, the program will generate ; a minimal FITS header. ; HEAP - A byte array giving the heap area following, e.g. a variable ; length binary table ; ; OPTIONAL INPUT KEYWORD: ; /APPEND - If this keyword is set then the supplied header and data ; array are assumed to be an extension and are appended onto ; the end of an existing FITS file. If the file does not ; exist, then WRITEFITS will create one with a minimal primary ; header (and /EXTEND keyword) and then append the supplied ; extension header and array. Note that the primary ; header in an existing file must already have an EXTEND ; keyword to indicate the presence of an FITS extension. ; /COMPRESS - If this keyword is set, then the FITS file is written as ; a gzip compressed file. An extension '.gz' is appended to ; to the file name if it does not already exist. The /COMPRESS ; option is incompatible with the /APPEND option. ; /Checksum - If set, then the CHECKSUM keywords to monitor data integrity ; will be included in the FITS header. For more info, see ; http://heasarc.gsfc.nasa.gov/docs/heasarc/fits/checksum.html ; NaNvalue - Value in the data array which represents missing pixels. ; This keyword is only used when missing pixels are not ; represented by NaN values in the input array. ; OUTPUTS: ; None ; ; RESTRICTIONS: ; (1) It recommended that BSCALE and BZERO not be used (or set equal ; to 1. and 0) with REAL*4 or REAL*8 data. ; (2) WRITEFITS will remove any group parameters from the FITS header ; ; EXAMPLE: ; Write a randomn 50 x 50 array as a FITS file creating a minimal header. ; ; IDL> im = randomn(seed, 50, 50) ;Create array ; IDL> writefits, 'test', im ;Write to a FITS file "test" ; ; PROCEDURES USED: ; CHECK_FITS, FITS_ADD_CHECKSUM, MKHDR, MRD_HREAD, SXDELPAR, SXADDPAR, ; SXPAR() ; ; MODIFICATION HISTORY: ; WRITTEN, Jim Wofford, January, 29 1989 ; Added call to IS_IEEE_BIG() W. Landsman Apr 96 ; Make sure SIMPLE is written in first line of header W. Landsman Jun 97 ; Use SYSTIME() instead of !STIME W. Landsman July 97 ; Create a default image extension header if needed W. Landsman June 98 ; Converted to IDL V5.0 W. Landsman June 98 ; Write unsigned data types W. Landsman December 1999 ; Update for IDL V5.3, add /COMPRESS keyword W. Landsman February 2000 ; Correct BZERO value for unsigned data W. Landsman July 2000 ; Eliminate duplication of input array if possible W. Landsman April 2001 ; Use FILE_SEARCH for V5.5 or later W. Landsman April 2002 ; Create the file if not already present and /APPEND is set ; W. Landsman September 2002 ; Proper call to MRD_HREAD if /APPEND is set W. Landsman December 2002 ; Added /CHECKSUM keyword W. Landsman December 2002 ; Restored NANvalue keyword, William Thompson, October 2003 ; Write BZERO in beginning of header for unsigned integers WL April 2004 ; Added ability to write heap array WL October 2004 ; Correct checksum if writing heap array WL November 2004 ;- On_error, 2 compile_opt idl2 ;For pre-V5.5 compatibility if N_params() LT 2 then begin print,'Syntax - WRITEFITS, filename, data,[ header, /APPEND, /CHECKSUM]' return endif ; Get information about data siz = size( data ) naxis = siz[0] ;Number of dimensions if naxis GT 0 then nax = siz[ 1:naxis ] ;Vector of dimensions lim = siz[ naxis+2 ] ;Total number of data points type = siz[naxis + 1] ;Data type ;Create a primary or image extension header if not supplied by the user if N_elements(header) LT 2 then begin if keyword_set(append) then mkhdr, header, data, /IMAGE $ else mkhdr, header, data, /EXTEND endif else if naxis GT 0 then $ check_FITS, data, header, /UPDATE, /FITS ; Remove any STSDAS/random group keywords from the primary header hdr = header if not keyword_set( APPEND) then begin simple = 'SIMPLE = T / Written by IDL: ' $ + systime() hdr[0] = simple + string( replicate(32b,80-strlen(simple) ) ) sxdelpar, hdr, [ 'GCOUNT', 'GROUPS', 'PCOUNT', 'PSIZE' ] endif ; If necessary,convert unsigned to signed. Do not destroy the original data if naxis NE 0 then begin unsigned = (type EQ 12) or (type EQ 13) if unsigned then begin if type EQ 12 then begin sxaddpar,hdr,'BZERO',32768,'Data is Unsigned Integer', $ before = 'DATE' newdata = fix(data - 32768) endif else if type EQ 13 then begin sxaddpar,hdr,'BZERO',2147483648,'Data is Unsigned Long', $ before = 'DATE' newdata = long(data - 2147483648) endif endif ; For floating or double precision test for NaN values to write NaNtest = keyword_set(NaNvalue) and ( (type EQ 4) or (type EQ 5) ) if NaNtest then begin NaNpts = where( data EQ NaNvalue, N_NaN) if (N_NaN GT 0) then begin if type EQ 4 then data[NaNpts] = !Values.F_NaN $ else if type EQ 8 then data[NaNpts] = !Values.D_NaN endif endif endif ; Open file and write header information if keyword_set( APPEND) then begin if (strmid( hdr[0],0,8 ) NE 'XTENSION') then begin message, $ 'ERROR - "XTENSION" must be first keyword in header extension',/CON return endif if !VERSION.RELEASE GE '5.5' then $ test = file_search(filename, COUNT = n) else $ test = findfile( filename, COUNT = n) if n EQ 0 then begin ;Create default primary header mkhdr,h0,0,/exten writefits,filename,0,h0, checksum = checksum openu, unit, filename, /BLOCK, /GET_LUN, /swap_if_little_endian endif else begin openu, unit, filename, /BLOCK, /GET_LUN, /swap_if_little_endian mrd_hread, unit, hprimary extend = where( strmid(hprimary,0,8) EQ 'EXTEND ', Nextend) if Nextend EQ 0 then begin message,'EXTEND keyword not found in primary FITS header',/CON message,'Recreate primary FITS header with EXTEND keyword ' + $ 'before adding extensions', /CON free_lun, unit return endif endelse file = fstat(unit) nbytes = file.size point_lun, unit, nbytes npad = nbytes mod 2880 if npad NE 0 then writeu, unit, replicate(32b, 2880 - npad) endif else begin ext = '' if keyword_set(COMPRESS) then $ if strlowcase(strmid(filename,2,3,/reverse)) NE '.gz' $ then ext = '.gz' $ else compress = 0 if !VERSION.OS EQ "vms" then $ openw, unit, filename +ext, /NONE, /BLOCK, /GET_LUN, 2880, $ /swap_if_little_endian,compress=compress else $ openw, unit, filename + ext, /GET_LUN, /swap_if_little_endian, $ compress = compress endelse ; Determine if an END line occurs, and add one if necessary endline = where( strmid(hdr,0,8) EQ 'END ', Nend) if Nend EQ 0 then begin message,'WARNING - An END statement has been appended to the FITS header',/INF hdr = [ hdr, 'END' + string( replicate(32b,77) ) ] endline = N_elements(hdr) - 1 endif ; Add any CHECKSUM keywords if desired if keyword_set(CHECKSUM) then begin if N_elements(heap) GT 0 then $ FITS_ADD_CHECKSUM, hdr, [data,heap] else $ FITS_ADD_CHECKSUM, hdr, data endline = where( strmid(hdr,0,8) EQ 'END ', Nend) endif nmax = endline[0] + 1 ; Convert to byte and force into 80 character lines bhdr = replicate(32b, 80l*nmax) for n = 0l, endline[0] do bhdr[80*n] = byte( hdr[n] ) npad = 80l*nmax mod 2880 writeu, unit, bhdr if npad GT 0 then writeu, unit, replicate(32b, 2880 - npad) ; Write data if naxis EQ 0 then goto, DONE bitpix = sxpar( hdr, 'BITPIX' ) nbytes = N_elements( data) * (abs(bitpix) / 8 ) npad = nbytes mod 2880 if unsigned then writeu, unit, newdata $ else writeu, unit, data ; Write optional heap area if N_elements(heap) GT 0 then begin theap = sxpar(hdr,'THEAP', Count=N_Theap) if N_Theap GT 0 then begin offset = theap - nbytes if offset GT 0 then begin writeu, unit, bytarr(offset) npad = (npad + offset) mod 2880 endif writeu, unit, heap npad = (npad + N_elements(heap)) mod 2880 endif endif ; ASCII Tables padded with blanks (32b) otherwise pad with zeros if keyword_set( APPEND) then begin exten = sxpar( header, 'XTENSION') if exten EQ 'TABLE ' then padnum = 32b else padnum = 0b endif else padnum = 0b if npad GT 0 then writeu, unit, replicate( padnum, 2880 - npad) DONE: free_lun, unit return end