some issues with legend

Development matplotlib-devel
1

When plotting interactively is it actually possible to update the
legend with the current plots while retaining the previous legend
settings (position, visibility, etc.) ?

here are some observations on the mpl legend operation:
leg = ax.get_legend() #0 OK. but the recommended way to update a
legend seems to be using #1 ?
leg = ax.legend() #1 OK
leg.draggable(True) #3 enables the legend to be moved with mouse.
New in mpl1.0.1. OK
leg.set_visible(False) #4 hides legend. OK
ax.legend(loc=3) #2 defines a legend location. OK but why no
locations outside the plotting area ?
ax.legend(ax.lines) #5 labels are different by default from #1. ??
ax.legend([]) #6 draws an empty square. ??
leg._loc: #7 allows you to know the legend location. in
#2 value is int, in #3 value is a tuple (if the legend has been moved)
OK but why is the attribute private ?

What to exclude from a legend :
Objects without an explicit label (labels starting with _) #8. OK
Objects that are not in the viewing area #9. should be default
behavior ??
Objects that are not set visible #10. should be default
behavior ??

···

--
thanks,
peter butterworth

2

When plotting interactively is it actually possible to update the
legend with the current plots while retaining the previous legend
settings (position, visibility, etc.) ?

I think it is possible, but will be quite difficult to do for a normal
user. I may try to add some method that can ease this.

here are some observations on the mpl legend operation:
leg = ax.get_legend() #0 OK. but the recommended way to update a
legend seems to be using #1 ?
leg = ax.legend() #1 OK
leg.draggable(True) #3 enables the legend to be moved with mouse.
New in mpl1.0.1. OK
leg.set_visible(False) #4 hides legend. OK
ax.legend(loc=3) #2 defines a legend location. OK but why no
locations outside the plotting area ?

Legend can be located outside the plotting area, anywhere you want.

http://matplotlib.sourceforge.net/users/legend_guide.html#legend-location

ax.legend(ax.lines) #5 labels are different by default from #1. ??

http://matplotlib.sourceforge.net/api/pyplot_api.html#matplotlib.pyplot.legend

If there is a single non-keyword argument, it is treated as a list of labels.

ax.legend() #6 draws an empty square. ??

To me, the current behavior seems reasonable. What do you expect?

leg._loc: #7 allows you to know the legend location. in
#2 value is int, in #3 value is a tuple (if the legend has been moved)
OK but why is the attribute private ?

I guess this is a valid point. I'll add a public interface to access this value.

What to exclude from a legend :
Objects without an explicit label (labels starting with _) #8. OK
Objects that are not in the viewing area #9. should be default
behavior ??
Objects that are not set visible #10. should be default
behavior ??

For #9, I don't think there is an exact algorithm to check if a path
is inside the viewing are or not when cubic splines are involved. If
there is (and that algorithm is feasible), we may consider making that
a default behavior. Otherwise, I'm not inclined to include a partial
solution.

For #10, I'll make it a default behavior if there is no objection.

Regards,

-JJ

···

On Sun, Jan 30, 2011 at 10:32 PM, Peter Butterworth <butterw@...149...> wrote:

--
thanks,
peter butterworth

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3

here are some observations on the mpl legend operation:

leg = ax.get_legend() #0 OK. but the recommended way to update a
legend seems to be using #1 ?
leg = ax.legend() #1 OK
leg.draggable(True) #3 enables the legend to be moved with mouse.
New in mpl1.0.1. OK
leg.set_visible(False) #4 hides legend. OK

ax.legend(loc=3) #2 defines a legend location. OK but why no
locations outside the plotting area ?
Legend can be located outside the plotting area, anywhere you want.
http://matplotlib.sourceforge.net/users/legend_guide.html#legend-location

Good to know.It is a bit more complex than a legend inside the axes though as you need to setup a bbox.

btw, there’s a typo in the html page: should be bbox_transform instead of transform in the doc:
“For example, if you want your axes legend located at the figure corner (instead of the axes corner):
l = legend(bbox_to_anchor=(0, 0, 1, 1), transform=gcf().transFigure)”

ax.legend(ax.lines) #5 labels are different by default from #1. ??
http://matplotlib.sourceforge.net/api/pyplot_api.html#matplotlib.pyplot.legend
If there is a single non-keyword argument, it is treated as a list of labels.

meaning that you always have to fully specify the labels.

ax.legend() #6 draws an empty square. ??
To me, the current behavior seems reasonable. What do you expect?

An empty square isn’t terribly useful and will likely need to be hidden. Could this form be used as to simply get rid of the legend instead ?

···

Le , Jae-Joon Lee <lee.j.joon@…149…> a écrit :

On Sun, Jan 30, 2011 at 10:32 PM, Peter Butterworth butterw@…149…> wrote: