Re: [Matplotlib-users] Updated Lasso Demo

[Eric B. <eri...@gm...>]

+1 for including Brian's changes in the shipping example.

Brian, You might also be interested in an alternate, polygon-based
lasso I developed a while back. Though it meets my needs, beware of
backend-specific problems with idle events that I never resolved.

-Eric

http://www.nabble.com/Alternate-lasso:-click-to-form-polygon-td18724261.html

On Sun, Dec 7, 2008 at 10:24 AM, B Clowers <clo...@ya...> wrote:
> When running the initial lasso demo I found that only one lasso event was
> allowed and other canvas interaction events (e.g. zooming) would not work
> properly after the lasso event.  As such I came up with my own solution to
> the problem by modifying the example source.  The primary addition was a
> button release event call and a boolean to keep track whether the lasso was
> the last event to lock the widget from interaction.  Anyway, I hope it can
> help someone else out.
>
> Cheers,
>
> Brian
>
> ####################################
> """
> Show how to use a lasso to select a set of points and get the indices
> of the selected points.  A callback is used to change the color of the
> selected points
>
> This is currently a proof-of-concept implementation (though it is
> usable as is).  There will be some refinement of the API and the
> inside polygon detection routine.
> """
> from matplotlib.widgets import Lasso
> import matplotlib.mlab
> from matplotlib.nxutils import points_inside_poly
> from matplotlib.colors import colorConverter
> from matplotlib.collections import RegularPolyCollection
>
> from matplotlib.pyplot import figure, show
> from numpy import nonzero
> from numpy.random import rand
>
> class Datum:
>     colorin = colorConverter.to_rgba('red')
>     colorout = colorConverter.to_rgba('green')
>     def __init__(self, x, y, include=False):
>         self.x = x
>         self.y = y
>         if include: self.color = self.colorin
>         else: self.color = self.colorout
>
>
> class LassoManager:
>     def __init__(self, ax, data):
>         self.axes = ax
>         self.canvas = ax.figure.canvas
>         self.data = data
>         #the lasso lock boolean is used to tell whether another
>         #widget event has priority
>         self.lassoLock = False
>
>         self.Nxy = len(data)
>
>         facecolors = [d.color for d in data]
>         self.xys = [(d.x, d.y) for d in data]
>         fig = ax.figure
>         self.collection = RegularPolyCollection(
>             fig.dpi, 6, sizes=(100,),
>             facecolors=facecolors,
>             offsets = self.xys,
>             transOffset = ax.transData)
>
>         ax.add_collection(self.collection)
>
>         self.cid = self.canvas.mpl_connect('button_press_event',
> self.onpress)
>         self.cidRelease = self.canvas.mpl_connect('button_release_event',
> self.onrelease)
>
>         self.ind = None
>
>     def callback(self, verts):
>         facecolors = self.collection.get_facecolors()
>         ind = nonzero(points_inside_poly(self.xys, verts))[0]
>         for i in range(self.Nxy):
>             if i in ind:
>                 facecolors[i] = Datum.colorin
>             else:
>                 facecolors[i] = Datum.colorout
>
>         self.canvas.draw_idle()
>         self.canvas.widgetlock.release(self.lasso)
>         #del self.lasso
>         self.ind = ind
>
>     def onpress(self, event):
>         if self.canvas.widgetlock.locked(): return
>         if event.inaxes is None: return
>         self.lasso = Lasso(event.inaxes, (event.xdata, event.ydata),
> self.callback)
>         # acquire a lock on the widget drawing
>         self.canvas.widgetlock(self.lasso)
>         # establish boolean that can be used to release the widgetlock
>         self.lassoLock = True
>
>     def onrelease(self, event):
>         'on release we reset the press data'
>         # test whether the widgetlock was initiated by the lasso
>         if self.lassoLock:
>             self.canvas.widgetlock.release(self.lasso)
>             self.lassoLock = False
>         print self.ind
>
>
> if __name__ == '__main__':
>
>     data = [Datum(*xy) for xy in rand(100, 2)]
>
>     fig = figure()
>     ax = fig.add_subplot(111, xlim=(0,1), ylim=(0,1), autoscale_on=False)
>     lman = LassoManager(ax, data)
>
>     show()
>
>
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