[AstroPy] Capturing pyfits warnings

[Bridgman, William T.]

try:
	fimg=pyfits.open(dfile)
except:
	whatever...

header=fimg[0].header

If warnings are warnings, this runs fine.

If warnings are elevated to exceptions, the pyfits.open throws the  
exception before loading fimg.  The fimg[0].header access fails.   
Putting fimg[0].header access inside the try: block doesn't help  
either (of course).

Perhaps inside the except: block I could set warnings back from  
exceptions to warnings and do pyfits.open again.  I don't know that  
much about python innards, but this sounds like something that would  
cause other weird (stack?) problems as I examine the 22,000+ FITS  
files in our data area.

Tom


On Sep 15, 2010, at 10:06 AM, jtaylor2 at stsci.edu wrote:

> Tom,
>
>   I am not sure I understand exactly what is going on here, but if  
> having the warnings module issue exceptions instead of warnings is  
> causing another warning to be raised as an exception that you would  
> like to remain as a warning, you can fix this by using  
> filterwarnings and supplying a regular expression that matches just  
> the warning that you want raised as an exception.  In your case  
> something like:
>
> warnings.filterwarnings('error',message='.*Warning:  File may have  
> been.*"')
>
>   If you contact me directly at jtaylor2 at stsci.edu with more  
> details, especially if you can point me to a fits file that is  
> causing the problem, I may be able to be of more help.
>
>     Jim T.

--
Dr. William T."Tom" Bridgman               Scientific Visualization  
Studio
Global Science & Technology, Inc.          NASA/Goddard Space Flight  
Center
Email: William.T.Bridgman at nasa.gov         Code 610.3
Phone: 301-286-1346                        Greenbelt, MD 20771
FAX:   301-286-1634                        http://svs.gsfc.nasa.gov/