[AstroPy] Equivalent expression for SXPAR from IDL in python

Martin Beroiz martinberoiz at gmail.com
Mon Feb 15 10:00:18 EST 2016


Hello,
This is how I get a single value of the header

from astropy.io <http://astropy.io/> import fits
naxis1 = fits.getval(“my filename.fits”, ’NAXIS1’)


M.
 
> On Feb 14, 2016, at 6:47 AM, Roberts, Michael <michael.roberts.15 at ucl.ac.uk> wrote:
> 
> I'm hoping this question is relatively straightforward for those proficient with IDL and python and fits file handling (I'm using the astropy.fits module)
> 
> I'm looking to find an equivalent to SXPAR (whose function is to obtain the value of a parameter in a FITS header) from IDL into python...
> 
> http://idlastro.gsfc.nasa.gov/ftp/pro/fits/sxpar.pro <http://idlastro.gsfc.nasa.gov/ftp/pro/fits/sxpar.pro>
> "sxpar.pro" - idlastro.gsfc.nasa.gov <http://idlastro.gsfc.nasa.gov/ftp/pro/fits/sxpar.pro>
> idlastro.gsfc.nasa.gov <http://idlastro.gsfc.nasa.gov/>
> Apostrophes are stripped ; from strings. If the parameter is logical, 1b is ; returned for T, and 0b is returned for F. ; If Name was of ...
> This is the original code in IDL:
> nxpix_uw1_ext1 = sxpar(hima_sk_uw1_ext1,'NAXIS1')
> nypix_uw1_ext1 = sxpar(hima_sk_uw1_ext1,'NAXIS2')
> This is my conversion attempt into python using astropy.fits:
> from astropy.io <http://astropy.io/> import fits
> 
> hima_sk_um2 = fits.open('') #Will contain the directory extension to the fits/img file I wish to open
> 
> # Compute the size of the images (you can also do this manually rather than calling these keywords from the header):
> nxpix_um2_ext1 = hima_sk_um2[1].header['NAXIS1']
> nypix_um2_ext1 = hima_sk_um2[1].header['NAXIS2']
> Firstly, is this correct? And secondly, is this the best way to handle an extension value?
> Any advise would be warmly received.
> Many thanks,
> Michael
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