无法使用PyFITS从拟合文件读取原始数据

Question

I'm trying to open a .fits file and read data from it using the pyFITS module for Python 2.7. Below is the code snippet which I'm running to try to attain the data from the file:

location = raw_input("Locaiton of FITS file: ") """user input location for the file"""
hdulist = pyfits.open(location) """opens the .fits file (works properly)"""

print(repr(hdulist[0].header)) """printed values shown below, works properly"""
pyfits.getdata(location, hdulist[0].header['TOTVALS']) """does NOT work"""

I know that the file's being opened properly; when I run print(repr(hdulist[0].header)) , the console shows

Warning (from warnings module):
  File "C:\Python27\lib\site-packages\pyfits\verify.py", line 69
    warnings.warn(u'Output verification result:')
UserWarning: Output verification result:

Warning (from warnings module):
  File "C:\Python27\lib\site-packages\pyfits\verify.py", line 73
    warnings.warn(line, VerifyWarning)
VerifyWarning: Card 'CRDER1' is not FITS standard (invalid value string: nan).  Fixed 'CRDER1' card to meet the FITS standard.

Warning (from warnings module):
  File "C:\Python27\lib\site-packages\pyfits\verify.py", line 74
    warnings.warn(u'Note: PyFITS uses zero-based indexing.\n')
UserWarning: Note: PyFITS uses zero-based indexing.


Warning (from warnings module):
  File "C:\Python27\lib\site-packages\pyfits\verify.py", line 69
    warnings.warn(u'Output verification result:')
UserWarning: Output verification result:

Warning (from warnings module):
  File "C:\Python27\lib\site-packages\pyfits\verify.py", line 73
    warnings.warn(line, VerifyWarning)
VerifyWarning: Card 'CRDER2' is not FITS standard (invalid value string: nan).  Fixed 'CRDER2' card to meet the FITS standard.

Warning (from warnings module):
  File "C:\Python27\lib\site-packages\pyfits\verify.py", line 74
    warnings.warn(u'Note: PyFITS uses zero-based indexing.\n')
UserWarning: Note: PyFITS uses zero-based indexing.


Warning (from warnings module):
  File "C:\Python27\lib\site-packages\pyfits\verify.py", line 69
    warnings.warn(u'Output verification result:')
UserWarning: Output verification result:

Warning (from warnings module):
  File "C:\Python27\lib\site-packages\pyfits\verify.py", line 73
    warnings.warn(line, VerifyWarning)
VerifyWarning: Card 'CSYSER1' is not FITS standard (invalid value string: nan).  Fixed 'CSYSER1' card to meet the FITS standard.

Warning (from warnings module):
  File "C:\Python27\lib\site-packages\pyfits\verify.py", line 74
    warnings.warn(u'Note: PyFITS uses zero-based indexing.\n')
UserWarning: Note: PyFITS uses zero-based indexing.


Warning (from warnings module):
  File "C:\Python27\lib\site-packages\pyfits\verify.py", line 69
    warnings.warn(u'Output verification result:')
UserWarning: Output verification result:

Warning (from warnings module):
  File "C:\Python27\lib\site-packages\pyfits\verify.py", line 73
    warnings.warn(line, VerifyWarning)
VerifyWarning: Card 'CSYSER2' is not FITS standard (invalid value string: nan).  Fixed 'CSYSER2' card to meet the FITS standard.

Warning (from warnings module):
  File "C:\Python27\lib\site-packages\pyfits\verify.py", line 74
    warnings.warn(u'Note: PyFITS uses zero-based indexing.\n')
UserWarning: Note: PyFITS uses zero-based indexing.

and then prints

SIMPLE  =                    T / file does conform to FITS standard             
BITPIX  =                   32 / number of bits per data pixel                  
NAXIS   =                    2 / number of data axes                            
NAXIS1  =                 4096 / length of data axis 1                          
NAXIS2  =                 4096 / length of data axis 2                          
EXTEND  =                    T / FITS dataset may contain extensions            
COMMENT   FITS (Flexible Image Transport System) format is defined in 'Astronomy
COMMENT   and Astrophysics', volume 376, page 359; bibcode: 2001A&A...376..359H 
DATE    = '2014-01-27T07:17:01'                                                 
DATE-OBS= '2014-01-27T06:34:10.00'                                              
TELESCOP= 'SDO/HMI'                                                             
INSTRUME= 'HMI_SIDE1'                                                           
WAVELNTH= 6173.0                                                                
CAMERA  =                    1                                                  
BUNIT   = 'Gauss'                                                               
ORIGIN  = 'SDO/JSOC-SDP'                                                        
CONTENT = 'MAGNETOGRAM'                                                         
QUALITY =                 1024                                                  
QUALLEV1=           1073741824                                                  
HISTORY Polynomial Coefficients used for Doppler velocity correction: 8.071746e+
HISTORY 01 5.340511e-03 -2.036568e-06 -7.976842e-10                             
COMMENT De-rotation: ON; Un-distortion: ON; Re-centering: ON; Re-sizing: OFF; co
COMMENT rrection for cosmic-ray hits; dpath=/home/jsoc/cvs/Development/JSOC/proj
COMMENT /lev1.5_hmi/apps/; linearity=1 with coefficients updated on 2014/01/15; 
COMMENT smooth=1; propagate eclipse bit from level 1; use of larger crop radius 
COMMENT look-up tables                                                          
BLD_VERS= '-802'                                                                
HCAMID  =                    2                                                  
SOURCE  = 'hmi.lev1_nrt[:#57580483,#57580411,#57580338,#57580272,#57580184,#575'
TOTVALS =             12841850                                                  
DATAVALS=             12841850    

...remaining values omitted...

The problem arises when I try pyfits.getdata(location, hdulist[0].header['TOTVALS']) . The error message returned is

Traceback (most recent call last):
  File "C:\Users\User\Desktop\openFITS.py", line 34, in <module>
    pyfits.getdata(location,hdulist[0].header['TOTVALS'])
  File "C:\Python27\lib\site-packages\pyfits\convenience.py", line 181, in getdata
    hdu = hdulist[extidx]
  File "C:\Python27\lib\site-packages\pyfits\hdu\hdulist.py", line 166, in __getitem__
    return super(HDUList, self).__getitem__(idx)
IndexError: list index out of range

print(len(hdulist)) returns 1; so I know that the index 0 shouldn't be out of range. Thus, the question is why I can't get the raw data in the header 'TOTVALS' from the hdulist, even though it seems that everything else is working fine.

Thanks in advance for your help!

Answer 1

The header you printed shows that the value of TOTVALS is 12841850.

You're trying to return the data from the 12841850th HDU. See: http://pyfits.readthedocs.org/en/v3.2.0/api_docs/api_files.html#getdata