find non-empty value in a dictionary

Dylan Reinhardt python at dylanreinhardt.com
Wed Apr 16 04:10:31 CEST 2003


What about:

if x:
   <stuff>
elif y:
   <stuff>

Etc, etc.  

Seems to work fine with a float value of 0.  There may be some edge case
where this doesn't work, but if there is, I haven't found it.

If you're just looking for the result (not which variable had the
non-zero value), you could do something like (untested):

result = max([d[var] / d['P'] for var in ['X','Y','Z']])

HTH,

Dylan



On Tue, 2003-04-15 at 18:26, matthew wrote:
> hi,
> 
> say you have a dictionay d =
> {'X': 0.0, 'Y'': 240.2, 'Z': 0.0, 'P': 13.3445}
> 
> where p divides pretty much evenly into Y; in this case approx 18
> 
> P will always be present and only one of X,Y,Z will have a non-zero value.
> 
> How can I easily find which X,Y, or Z is non-zero; esp. given that 
> comparing floats is 'inaccurate' as in:
> 
> if X != 0:
> 	<stuff>
> elif Y != 0:
> 	<stuff>
> elif Z != 0:
> 	<stuff>
> else:
> 	<stuff-up>
> 
> Also, once the correct axis is found,  exactly the same maths will be 
> applied which means that in the above, the same statement will be 
> replicated excepting the axis variable. any ideas on the best pythonic 
> way to tackle this?
> 
> any hints on best practice with comparing floats.
> 
> Thanks. matthew.
> 
> 






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