Re: [Matplotlib-users] pick markers only but not the connecting line

[C M <cmp...@gm...>]

Great, thanks for all the help!


On Sun, Jun 8, 2014 at 12:09 AM, Eric Firing <ef...@ha...> wrote:

> On 2014/06/07, 5:03 PM, C M wrote:
> >
> >
> >
> > On Sat, Jun 7, 2014 at 10:18 PM, Eric Firing <ef...@ha...
> > <mailto:ef...@ha...>> wrote:
> >
> >     On 2014/06/07, 4:12 PM, C M wrote:
> >      > I had been using a custom function (written originally by
> >     Jae-Joon and
> >      > modified a little by me...quite a long time back now) that was
> >     working
> >      > to allow point picking of markers, but *not* the line connecting
> >     them.
> >      > However, I've now discovered with the help of this list that the
> >      > function I am using has the disadvantage that if there are more
> >     than 100
> >      > data points, I can't get the correct index for the picked marker
> >     (turned
> >      > out not to be a mpl bug:
> >      > https://github.com/matplotlib/matplotlib/issues/3124).
> >      >
> >      > So I can just use the default pick event, but then the user can
> pick
> >      > anywhere on the connecting line, which is meaningless in this
> >     use--so I
> >      > don't want them to be able to pick on the connecting line.
> >
> >     Why not just execute plot twice, once with the markers, with picking
> >     activated, and a second time with the line, with picking inactive
> (the
> >     default).
> >
> >     Eric
> >
> >
> > That is so simple, and I hadn't thought of it at all.  Thank you!  My
> > only concerns would be for slowness of plotting if there are a lot of
> > points and just code simplicity, and so if there could be some other way
> > with a custom function for the picker that would do this, I would
> > probably prefer that. But maybe neither of these are particularly
> > important concerns.
>
> I think you will find plotting two lines instead of one is not at all
> prohibitive with respect to speed; especially when you are zooming, so
> that the number of points being plotted is not so large.
>
> As for simplicity, two calls to a standard function with almost the same
> arguments beats an arcane special-purpose function!
>
> If you want to make your own picker, though, it looks like you could use
> a slight modification of Line2D.contains(); it would be just a matter of
> copying it and replacing this section
>
>              # Check for collision
>              if self._linestyle in ['None', None]:
>                  # If no line, return the nearby point(s)
>                  d = (xt - mouseevent.x) ** 2 + (yt - mouseevent.y) ** 2
>                  ind, = np.nonzero(np.less_equal(d, pixels ** 2))
>              else:
>                  # If line, return the nearby segment(s)
>                  ind = segment_hits(mouseevent.x, mouseevent.y, xt, yt,
> pixels)
>
>
> with the code in the first option--that is, without checking the
> _linestyle.  You would also need to remove the first two lines after the
> docstring.
>
> Eric
>
> >
> > Che
> >
> >
> >
> >
> >
> >
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