[Casa-framework] Added quanta tool to casapy

[Wim.Brouw at csiro.au]

The observation that all the string conversion takes place in glish for say '12:09:12.13' or '12km/s2' is incorrect.
If a string is input to the 'quantity' method the c++ ('quant') is called to convert it to a quantity.
(would have been very expensive to do it all in glish)

Wim
 

> -----Original Message-----
> From: casa-framework-bounces at donar.cv.nrao.edu 
> [mailto:casa-framework-bounces at donar.cv.nrao.edu] On Behalf 
> Of Raymond Rusk
> Sent: Friday, 15 September 2006 07:04
> To: Kumar Golap
> Cc: casa-framework at nrao.edu
> Subject: Re: [Casa-framework] Added quanta tool to casapy
> 
> On Thu, 14 Sep 2006, Kumar Golap wrote:
> 
> > An observation  I have
> > 
> > Design wise ....right now quanta.quantity is not more useful that 
> > quantity alone to use...
> > 
> > because i need to use a float and a string....e.g so i need 
> to convert 
> > myself to a float something i know in hours mins and seconds
> > 
> > if you look at the quanta examples in glish
> > 
> > http://aips2.aoc.nrao.edu/docs/user/General/node474.html#quanta
> > 
> > 
> > it can interprete  a string and convert it to the right 
> quatitty and 
> > units
> > 
> > qa.quantity('12h00m00')
> > 
> > gets converted to a time quamntity [0.5,''d']
> > 
> > qa.quantity('180d00m00')
> > 
> > gets converted to an angle quantity [3.142, 'rad')
> > 
> > 
> > etc etc...
> > 
> > So will that be possible to implement.
> 
> As it is currently implemented, quantities can be expressed 
> in canonical units using:
> 	t=qa.canonical(qa.quantity(12.,'h'))
> 	print qa.tos(t)
>  and 
> 	a=qa.canonical(qa.quantity(180.,'deg')).
> 	print qa.tos(a).
> 
> You should also be able to use the convert method to specify 
> exactly which units that you want.  (Note that I haven't done 
> much testing yet as I have just gotten this component into casapy.)
> 
> I think your real question is whether can you enter the string '12h' 
> rather than qa.quantity(12.,'h').  The answer is yes, this 
> can be implemented, but all of our string handling capability 
> is in the Glish code and will take time to translate to C++.
> 
> Also, there is a design choice.  Most of the Glish methods 
> take a string or a quantity.  If the input parameter is a 
> string then the Glish code parses it and, when it has the 
> expected format, converts it to a quantity before passing it 
> on to the C++ method.
> 
> If the C++ methods defined by the IDL need to accept either 
> strings or quantities then I will need to use a record or 
> variant to pass parameters.  
> I am not sure whether that would be better or not.  Every 
> method would also have the added overhead of dealing with the records.
> 
> It might be better to do something on the Python end to 
> convert strings to quantities in analogy with the glish.  
> Then the C++ methods don't have the added overhead of string 
> conversion code if it isn't needed.
> 
> Anyway, I nearly certainly will not have time this month to 
> write the code needed to generate valid quantities from 
> arbitrary strings since there is considerable work to be done 
> on the atmosphere component.  Also, rather than using the 
> existing Glish code as the specification, it would be better 
> to start from a formal specification of string formats that 
> should be parsed.
> 
> > thanks
> > 
> > Kumar
> > 
> > 
> > 
> > 
> > 
> > On 9/14/06, Raymond Rusk <Raymond.Rusk at nrc-cnrc.gc.ca> wrote:
> > > Hi,
> > >
> > > Quit a bit of the quanta tool is functional so I have added it to 
> > > code/casac/scripts/casapy.py so that it can be exercised.  For my 
> > > build, I had to run 'gmake componentslib' afterwards to 
> make it available.
> > >
> > > Raymond
> > >
> > > --
> > > Dr. Raymond Rusk                                        
> Dr. Raymond Rusk
> > > ALMA Software Engineer                           
> Ing?nieur Logiciel ALMA
> > > National Research Council Canada   Conseil national de 
> recherches Canada
> > > Herzberg Institute of Astrophysics   L'Institut Herzberg 
> d'Astrophysique
> > > DRAO, P.O. Box 248                                    
> OFRA, B.P. Box 248
> > > Penticton, BC V2A 6J9           |\^/|         Penticton, 
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> > > Fax: (250)493-7767            >_./|\._<               
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> > > Raymond.Rusk at nrc-cnrc.gc.ca                  
> Raymond.Rusk at nrc-cnrc.gc.ca
> > >
> > 
> > 
> 
> -- 
> Dr. Raymond Rusk                                        Dr. 
> Raymond Rusk
> ALMA Software Engineer                           Ingénieur 
> Logiciel ALMA
> National Research Council Canada   Conseil national de 
> recherches Canada
> Herzberg Institute of Astrophysics   L'Institut Herzberg 
> d'Astrophysique
> DRAO, P.O. Box 248                                    OFRA, 
> B.P. Box 248
> Penticton, BC V2A 6J9           |\^/|         Penticton, 
> (C.-B.) V2A 6J9
> Government of Canada         _|\|   |/|_          
> Gouvernement du Canada
> Tel: (250)490-4347           >         <              Tél: 
> (250)490-4347
> Fax: (250)493-7767            >_./|\._<               Fax: 
> (250)493-7767
> Raymond.Rusk at nrc-cnrc.gc.ca                  
> Raymond.Rusk at nrc-cnrc.gc.ca
>