8000 Simplify lasso_demo example. · matplotlib/matplotlib@99b5f0b · GitHub
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Simplify lasso_demo example.
- No need for a separate Datum data model, which feels a bit overengineered. - Showing how to directly use the collection's array to store the relevant info and colormapping for display purposes seems more interesting. This also allows directly using the return value of contains_point() to update the collection's array. - In general it is a good idea to not store a reference to the canvas (which can be swapped underneath you).
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‎galleries/examples/event_handling/lasso_demo.py

Lines changed: 25 additions & 65 deletions
Original file line numberDiff line numberDiff line change
@@ -3,12 +3,8 @@
33
Lasso Demo
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==========
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6-
Show how to use a lasso to select a set of points and get the indices
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of the selected points. A callback is used to change the color of the
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selected points
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This is currently a proof-of-concept implementation (though it is
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usable as is). There will be some refinement of the API.
6+
Use a lasso to select a set of points and get the indices of the selected points.
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A callback is used to change the color of the selected points.
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.. note::
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This example exercises the interactive capabilities of Matplotlib, and this
@@ -28,79 +24,43 @@
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from matplotlib.widgets import Lasso
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class Datum:
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colorin = mcolors.to_rgba("red")
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colorout = mcolors.to_rgba("blue")
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def __init__(self, x, y, include=False):
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self.x = x
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self.y = y
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if include:
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self.color = self.colorin
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else:
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self.color = self.colorout
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class LassoManager:
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def __init__(self, ax, data):
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self.axes = ax
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self.canvas = ax.figure.canvas
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self.data = data
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self.Nxy = len(data)
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facecolors = [d.color for d in data]
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self.xys = [(d.x, d.y) for d in data]
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# The information of whether a point has been selected or not is stored in the
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# collection's array (0 = out, 1 = in), which then gets colormapped to blue
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# (out) and red (in).
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self.collection = RegularPolyCollection(
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6, sizes=(100,),
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facecolors=facecolors,
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offsets=self.xys,
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offset_transform=ax.transData)
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6, sizes=(100,), offset_transform=ax.transData,
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offsets=data, array=np.zeros(len(data)),
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clim=(0, 1), cmap=mcolors.ListedColormap(["tab:blue", "tab:red"]))
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ax.add_collection(self.collection)
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self.cid_press = self.canvas.mpl_connect('button_press_event',
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self.on_press)
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self.cid_release = self.canvas.mpl_connect('button_release_event',
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self.on_release)
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canvas = ax.figure.canvas
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canvas.mpl_connect('button_press_event', self.on_press)
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canvas.mpl_connect('button_release_event', self.on_release)
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def callback(self, verts):
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facecolors = self.collection.get_facecolors()
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p = path.Path(verts)
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ind = p.contains_points(self.xys)
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for i in range(len(self.xys)):
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if ind[i]:
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facecolors[i] = Datum.colorin
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else:
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facecolors[i] = Datum.colorout
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self.canvas.draw_idle()
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data = self.collection.get_offsets()
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self.collection.set_array(path.Path(verts).contains_points(data))
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canvas = self.collection.figure.canvas
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canvas.draw_idle()
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del self.lasso
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def on_press(self, event):
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if self.canvas.widgetlock.locked():
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canvas = self.collection.figure.canvas
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if event.inaxes is not self.collection.axes or canvas.widgetlock.locked():
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return
83-
if event.inaxes is None:
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return
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self.lasso = Lasso(event.inaxes,
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(event.xdata, event.ydata),
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self.callback)
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# acquire a lock on the widget drawing
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self.canvas.widgetlock(self.lasso)
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self.lasso = Lasso(event.inaxes, (event.xdata, event.ydata), self.callback)
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canvas.widgetlock(self.lasso) # acquire a lock on the widget drawing
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def on_release(self, event):
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if hasattr(self, 'lasso') and self.canvas.widgetlock.isowner(self.lasso):
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self.canvas.widgetlock.release(self.lasso)
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canvas = self.collection.figure.canvas
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if hasattr(self, 'lasso') and canvas.widgetlock.isowner(self.lasso):
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canvas.widgetlock.release(self.lasso)
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if __name__ == '__main__':
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np.random.seed(19680801)
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100-
data = [Datum(*xy) for xy in np.random.rand(100, 2)]
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ax = plt.axes(xlim=(0, 1), ylim=(0, 1), autoscale_on=False)
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ax.set_title('Lasso points using left mouse button')
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104-
lman = LassoManager(ax, data)
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63+
ax = plt.figure().add_subplot(
64+
xlim=(0, 1), ylim=(0, 1), title='Lasso points using left mouse button')
65+
manager = LassoManager(ax, np.random.rand(100, 2))
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plt.show()

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