matplotlib-devel Mailing List for matplotlib

I committed the original example into the svn, and I admit that I was
not careful with the code. I agree that the arguments should be float
(the doc does say that set_alpha takes float).
The example is now updated to use floats (svn r7300).

Regards,

-JJ


On Mon, Jul 27, 2009 at 9:15 AM, Michiel de Hoon<mjl...@ya...> wrote:
>
> Hi everybody,
>
> Should the set_alpha method of a graphics context accept a string (instead of a number) as an argument? Currently, some backends (agg, ps, pdf) accept strings such as "0.2", whereas others (svg, cairo, Mac OS X) do not. Usually that is not a problem, since in almost all cases set_alpha is called with a number as the argument. However, the example axes_zoom_effect.py, which was recently added to examples/pylab_examples, has these lines:
>
>    prop_patches["alpha"]="0.2"
>
> which causes a call to gc.set_alpha of the form gc.set_alpha("0.2"). Backends that do not allow strings choke on that.
>
> Whereas in general it may perhaps be useful to allow such strings, it adds complexity to the code, and I don't see a good use case for it.
>
> --Michiel.
>
>
>
>
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In svn 7298 I changed a key chunk of code that was working fine, so I 
would like to explain why I fixed it when it wasn't broken, and ask for 
review and testing, or at least keeping your eyes open for anything I 
may have overlooked.

In the course of making the very simple change to support scalar 
arguments to plot (for plotting a single symbol), I found, as I have 
many times before, that the argument handling was rather complex, 
repetitive, and hard to follow.  I couldn't resist seeing if I could 
simplify it, in the hope that this would make it easier to maintain. 
The result is a reduction in LOC and a codepath that to my eye, at 
least, is easier to follow.

Eric

Hi everybody,

Should the set_alpha method of a graphics context accept a string (instead of a number) as an argument? Currently, some backends (agg, ps, pdf) accept strings such as "0.2", whereas others (svg, cairo, Mac OS X) do not. Usually that is not a problem, since in almost all cases set_alpha is called with a number as the argument. However, the example axes_zoom_effect.py, which was recently added to examples/pylab_examples, has these lines:

    prop_patches["alpha"]="0.2"

which causes a call to gc.set_alpha of the form gc.set_alpha("0.2"). Backends that do not allow strings choke on that.

Whereas in general it may perhaps be useful to allow such strings, it adds complexity to the code, and I don't see a good use case for it.

--Michiel.