Re: [matplotlib-devel] new legend interface and WXAgg interactive mode

[John H. <jd...@gm...>]

On Tue, Sep 16, 2008 at 2:14 PM, Jack Sankey <jac...@gm...> wrote:
> Hello,
> I couldn't find this in the API changes, but when I upgraded to the latest
> matplotlib 0.98.2, I found (after much hair pulling) that
> gca().plot([1,2,1], label='_anything')
> will produce a plot and
> gca().legend()
> will not display the specified label. I had been using filenames starting
> with underscores before and _nolabel_ to keep from showing a legend entry.
> Is this a bug or has the philosophy changed to eliminate anything starting
> with an underscore from the legend? I think if anything None or maybe ""
> should be used for empty labels.

I had to check the code to see why this was so, but we do exclude
everything that starts with an underscore, even though we only
document the '_nolegend_'.  I suspect that this change was designed to
support the autolabeling of lines when added without a label.  In
Axes.add_line:

        if not line.get_label():
            line.set_label('_line%d'%len(self.lines))

but I don't recall why we added this bit of functionality.  I'm not
sure at this point if we should change the doc to reflect reality or
change reality to reflect the doc, so perhaps someone using the
auto-labeled line feature should chime in here.


> Second, I am using interactive mode and WXAgg in windows. So my startup
> script does this:
> import matplotlib as _mpl
> _mpl.use('WXAgg')
> import pylab as _p
> _p.ion()
> Before, when I would then type
> gca().plot([1,2,1])

I would not expect a draw here, since draw only happens on pylab
commands.  Eg _p.plot should trigger a draw, but not gca().plot
because the latter is an axes method.  I don't really know why it
would have worked before, if it did.  I would be pretty surprised if
it did, actually.

JDH