Re: [Matplotlib-users] legend marker update problem

[Sterling S. <sm...@fu...>]

Gregorio,

I experienced a similar issue with trying to change the marker color.  

See below the previous response from JJ for accessing the legend marker or using a proxy artist.

-Sterling

> On Sep 4, 2012, at 5:33PM, Jae-Joon Lee wrote:
> 
> On Wed, Sep 5, 2012 at 6:05 AM, Sterling Smith <sm...@fu...> wrote:
>> I still do not get black markers.  Furthermore, if you try to make a new legend with the result of leg.get_lines(), you will get lines without markers, which leads me to the conclusion I stated in my previous email (which you did not copy)
>>>> I suspect that this is because the legend marker is drawn separately from the legend line to accommodate the numpoints argument of the legend functions.  Then the question is how to access these markers if they are separate from the line2d objects in the legend.  I didn't even see them in the children of the legend [legend.get_children()].
> 
> This is correct. To support legend handle like --o-- (i.e., no markers
> at the ends), lines and markers are drawn as a separate artist. You
> may use something like,
> 
> line[0]._legmarker.set_markerfacecolor('black')
> line[1]._legmarker.set_markerfacecolor('black')
> 
> I, personally, recommend you to use a proxy artist.
> 
> http://matplotlib.sourceforge.net/users/legend_guide.html#using-proxy-artist
> 
> For example,
> 
> You may do something like
> 
> import pylab
> pylab.plot(pylab.linspace(0,1,100),marker='o',ls='')
> pylab.plot(pylab.linspace(0,1,100),marker='o',ls='-')
> 
> # creates artists for legend purpose only
> l1, = pylab.plot(pylab.linspace(0,1,100), 'ko-')
> l2, = pylab.plot(pylab.linspace(0,1,100), 'ko')
> # remove them from the axes.
> l1.remove()
> l2.remove()
> 
> leg=pylab.legend([l1, l2], ["Test 1", "Test 2"], loc='best')
> 
> Regards,
> 
> -JJ
On May 16, 2013, at 7:25AM, Gregorio Bastardo wrote:

> Hi,
> 
> I've recently come accross an issue when working on an interactive
> marker toggling callback. The problem is illustrated below:
> 
> import matplotlib.pyplot as plt
> fig = plt.figure()
> ax = fig.add_subplot(111)
> line, = ax.plot(range(10), range(10))
> # uncomment next line to reproduce bug
> # line.set_marker('d')
> legend = ax.legend([line], ['foo'])
> legend_line, = legend.get_lines()
> fig.show()
> raw_input('press enter to clear marker')
> line.set_marker('')
> legend_line.set_marker('')
> fig.canvas.draw()
> raw_input('press enter to set marker')
> line.set_marker('d')
> legend_line.set_marker('d')
> fig.canvas.draw()
> raw_input('press enter to exit')
> 
> So when I add a line object to the legend *without marker*, the update
> works fine both on data and legend line, but *with marker* it does not
> refresh the legend line. I consider it as a bug, please tell me if I'm
> doing something wrong.
> 
> python 2.7.4 win32
> matplotlib 1.2.1
> 
> Thanks,
> Gregorio
> 
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