Hello. In case it is of use to anyone, here is a
revised lasso_demo.py that draws a polygon around
selected points, deletes points with a click of the
middle mouse button, and adds points with a right
click. Thanks John H for the help getting started.
I am just learning and do have a couple of questions.
Why is the lock on lasso needed in the original demo.
For my revised version, it works better without it (a
right click without dragging caused an infinite lock).
Also, I would have expected the callback function to
be executed directly on execution of the self.lasso =
Lasso(...) line in the onpress function, but instead
it is executed after the last line of the onpress
function. Why is this?
"""
draws a polygon around points selected with the mouse
deletes points selected with a middle click
adds points selected with a right click
"""
import os
from numpy import *
import glob
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.patches import Polygon
from pylab import figure, show, nx
import pdb
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.flag = flag
self.axes = ax
self.canvas = ax.figure.canvas
self.data = data
self.Nxy = len(data)
self.facecolors = [d.color for d in data]
self.xys = [(d.x, d.y) for d in data]
self.collection = RegularPolyCollection(
fig.dpi, 6, sizes=(100,),
facecolors=self.facecolors,
offsets = self.xys,
transOffset = ax.transData)
ax.add_collection(self.collection)
self.cid =
self.canvas.mpl_connect('button_press_event',
self.onpress)
def callback(self, verts):
ind = nx.nonzero(points_inside_poly(self.xys,
verts))
if len(ind) == 0:
return
for i in range(self.Nxy):
if i in ind:
self.facecolors[i] = Datum.colorin
else:
self.facecolors[i] = Datum.colorout
self.canvas.draw_idle()
self.canvas.widgetlock.release(self.lasso)
# draw polygon
if len(self.axes.patches) > 0:
self.axes.patches.pop()
xyo=list()
for i in ind:
xyo.append(self.xys[i])
rect = Polygon(xyo, facecolor='red', alpha=0.5)
self.axes.add_patch(rect)
self.canvas.draw_idle()
del self.lasso
def onpress(self, event):
if self.canvas.widgetlock.locked():
return
if event.inaxes is None:
return
if event.button == 3:
ax.collections[0]._offsets.append((event.xdata,event.ydata))
ax.collections[0]._facecolors.append(colorConverter.to_rgba('blue'))
self.canvas.draw_idle()
return
if event.button == 2:
d = list()
for i in ax.collections[0]._offsets:
dis = sqrt( (event.xdata - i[0])**2 +
(event.ydata - i[1])**2 )
d.append(dis)
minn = min(d)
minID = d.index(minn)
ax.collections[0]._offsets.pop(minID)
ax.collections[0]._facecolors.pop(minID)
self.canvas.draw_idle()
self.Nxy = self.Nxy-1
return
self.lasso = Lasso(event.inaxes,(event.xdata,
event.ydata), self.callback)
# acquire a lock on the widget drawing
# self.canvas.widgetlock(self.lasso)
data = [Datum(*xy) for xy in nx.mlab.rand(100,2)]
fig = figure()
ax = fig.add_subplot(111, xlim=(0,1), ylim=(0,1),
autoscale_on=False)
flag = 0
lman = LassoManager(ax, data)
ax.grid('on')
show()
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