.. _widgets-lasso_selector_demo: widgets example code: lasso_selector_demo.py ============================================ [`source code `_] :: from __future__ import print_function import numpy as np from matplotlib.widgets import LassoSelector from matplotlib.path import Path try: raw_input except NameError: # Python 3 raw_input = input class SelectFromCollection(object): """Select indices from a matplotlib collection using `LassoSelector`. Selected indices are saved in the `ind` attribute. This tool highlights selected points by fading them out (i.e., reducing their alpha values). If your collection has alpha < 1, this tool will permanently alter them. Note that this tool selects collection objects based on their *origins* (i.e., `offsets`). Parameters ---------- ax : :class:`~matplotlib.axes.Axes` Axes to interact with. collection : :class:`matplotlib.collections.Collection` subclass Collection you want to select from. alpha_other : 0 <= float <= 1 To highlight a selection, this tool sets all selected points to an alpha value of 1 and non-selected points to `alpha_other`. """ def __init__(self, ax, collection, alpha_other=0.3): self.canvas = ax.figure.canvas self.collection = collection self.alpha_other = alpha_other self.xys = collection.get_offsets() self.Npts = len(self.xys) # Ensure that we have separate colors for each object self.fc = collection.get_facecolors() if len(self.fc) == 0: raise ValueError('Collection must have a facecolor') elif len(self.fc) == 1: self.fc = np.tile(self.fc, self.Npts).reshape(self.Npts, -1) self.lasso = LassoSelector(ax, onselect=self.onselect) self.ind = [] def onselect(self, verts): path = Path(verts) self.ind = np.nonzero([path.contains_point(xy) for xy in self.xys])[0] self.fc[:, -1] = self.alpha_other self.fc[self.ind, -1] = 1 self.collection.set_facecolors(self.fc) self.canvas.draw_idle() def disconnect(self): self.lasso.disconnect_events() self.fc[:, -1] = 1 self.collection.set_facecolors(self.fc) self.canvas.draw_idle() if __name__ == '__main__': import matplotlib.pyplot as plt plt.ion() data = np.random.rand(100, 2) subplot_kw = dict(xlim=(0, 1), ylim=(0, 1), autoscale_on=False) fig, ax = plt.subplots(subplot_kw=subplot_kw) pts = ax.scatter(data[:, 0], data[:, 1], s=80) selector = SelectFromCollection(ax, pts) plt.draw() raw_input('Press any key to accept selected points') print("Selected points:") print(selector.xys[selector.ind]) selector.disconnect() # Block end of script so you can check that the lasso is disconnected. raw_input('Press any key to quit') Keywords: python, matplotlib, pylab, example, codex (see :ref:`how-to-search-examples`)