Re: [matplotlib-devel] faulty design for Lasso widget?

[Benjamin R. <ben...@ou...>]

On Tue, Feb 28, 2012 at 10:58 AM, John Hunter <jd...@gm...> wrote:

>
>
> On Tue, Feb 28, 2012 at 10:44 AM, Benjamin Root <ben...@ou...> wrote:
>
>>
>> The Lasso disconnects itself after the button_release event because
>> that's what indicates that you are done.  The user gets back a single
>> Line2D object that is assumed to represent a single path with no breaks.
>> Reusing the Lasso widget would be a situation that would require a
>> different idiom for user interaction.  I wouldn't be against a "MultiLasso"
>> widget that works differently from Lasso, but I really wouldn't want to
>> make changes to existing user widgets.  It is iffy enough about whether to
>> remove the point-count-check.
>>
>>
> I added the point count check according to git blame and I don't remember
> why but I agree is doesn't look like it makes sense to me.  I think this
> lasso is lightly used based on the volume of questions we get about it.
>  One reason it may be lightly used is because it is hard to work with.  If
> we can improve it, even changing functionality,  I would be in favor.  Eg,
> allowing the same Lasso to handle repeated selections makes sense to me.
>  If the change looks too onerous, we could call it Lasso2 and deprecate the
> former.
>

I think that logic is slightly faulty.  Another reason why we don't get a
lot of questions about it could be because it does (almost) exactly what
users want.  Currently, I use the Lasso widget in my track_maker project to
select storm cells in a movie of radar images.  Because I have multiple
modes to the program, a persistent Lasso object makes little sense. I also
want the Lasso's line to disappear after I am done selecting it so that I
can put in a polygon patch of my coloring and hatching.

I am skeptical of any redesign of Lasso.  I am willing to see what others
have in mind, but I still think that it might better belong in a new class
"MultiLasso".  I see no reason to deprecate the current Lasso (only to fix
it).

Cheers!
Ben Root