Re: [Gnuplot-py-users] Gnuplot.py float precision (again)

[Xaver W. <xav...@we...>]

Hi,
basically, I agree, we probably don't need to raise an exception. However,

 isinstance(m, numpy.ndarray)

returns 'True' for any valid numpy array, which includes e. g. string arrays, 
and for a non-gnuplot compatible array the error message with your code is

gnuplot> plot "/tmp/tmpndt27x.gnuplot/fifo" notitle
              ^
         line 0: Bad data on line 1

..not very helpful. I'd propose to rather have explicitly permitted array 
types, like

     if m.dtype.name in ('float64','float32','int32',int64'):
         return m
     else:
         return numpy.array(m,dtype=numpy.float32)

whereas the 'else' clause serves mainly for having a defined error message, 
maybe intercepted by a 'try...except'.

This might also eliminate the redundant conversion from float32 to float32 (if 
python/numpy is not intelligent enough to not do that). What about int32 / 
int64 arrays? It would be just fine to not convert them as well, right? Saves 
memory, I guess...

Xaver

P.S.:
Is
diff --context oldfile.py oldfile_new.py >> mypatch.py.patch
the right way to make a patch file for the tracker? I've never done that 
before...


Am Dienstag, 3. März 2009 14:40:51 schrieb Alan G Isaac:
> You are correct: the try clause now succeeds
>
> because downcasting is allowed:
>      >>> x = np.random.random((5,))
>      >>> x.dtype
>
>      dtype('float64')
>
>      >>> x32 = x.astype(np.float32)
>      >>> x32.dtype
>
>      dtype('float32')
>
> How about returning any ndarray untouched?
>
>      if isinstance(m, numpy.ndarray):
>          return m
>      else:
>          return numpy.array(m,dtype=numpy.float32)
>
> I see no need to print an error message:
> NumPy will report appropriately.
>
> Alan Isaac
>
>
>
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