互动图Chaco，性状通知中出现异常

Question

我正在使用Chaco库。我制作了一个交互式绘图，在这个绘图中，使用chaco.tools.api RangeSelection，我可以选择其中的一部分。现在，我想知道这个矩形在什么位置。使用以下代码，我可以做我需要的所有事情，但我有以下错误，为什么？？在错误中，指向I nedd的点是selection_mmask

这是代码：

# Major library imports
from numpy import arange
from scipy.special import jn
# Enthought library imports
from enable.api import Component, ComponentEditor
from traits.api import HasTraits, Instance, Any, on_trait_change
from traitsui.api import Item, Group, View
# Chaco imports
from chaco.api import create_line_plot, add_default_axes, add_default_grids
from chaco.tools.api import RangeSelection, RangeSelectionOverlay
# # Create the Chaco plot.
def _create_plot_component(self):
    numpoints = 100
    low = -5
    high = 15.001
    x = arange(low, high, (high-low)/numpoints)
    # Plot a bessel function
    y = jn(0, x)
    plot = create_line_plot((x,y), color=(0,0,1,1), width=2.0, index_sort="ascending")
    plot.active_tool = RangeSelection(plot, left_button_selects = True,     auto_handle_event = False)
    plot.overlays.append(RangeSelectionOverlay(component=plot))
    plot.bgcolor = "white"
    plot.padding = 50
    add_default_grids(plot)
    add_default_axes(plot)
    self.times_ds = plot.index
    self.times_ds.on_trait_change(self._selections_changed, 'metadata_changed')
    return plot
# Attributes to use for the plot view.
size=(600,500)
title="Simple line plot"
class Demo(HasTraits):
    times_ds = Any()
    plot = Instance(Component)
    corr_renderer = Any()
    traits_view = View(
                    Group(
                        Item('plot', editor=ComponentEditor(size=size),
                             show_label=False),
                        orientation = "vertical"),
                    resizable=True, title=title,
                    width=size[0], height=size[1]
                    )
    def _plot_default(self):
         return _create_plot_component(self)
    def _selections_changed(self, event):
        selections = event["selections"]
        low, high = selections
        print low, high
demo = Demo()
if __name__ == "__main__":
    demo.configure_traits()

这是误差的一部分（误差中是矩形的点到I nedd）

Exception occurred in traits notification handler for object:   <chaco.array_data_source.ArrayDataSource object at 0x66a94d0>, trait: metadata_changed, old  value: <undefined>, new value: True
Traceback (most recent call last):
  File "/home/franco/Python/Canopy/appdata/canopy-1.0.3.1262.rh5-x86_64/lib/python2.7/site-packages/traits/trait_notifiers.py", line 521, in rebind_call_1
    self.dispatch( getattr( obj(), self.name ), new )
  File "/home/franco/Python/Canopy/appdata/canopy-1.0.3.1262.rh5-x86_64/lib/python2.7/site-packages/traits/trait_notifiers.py", line 455, in dispatch
handler( *args )
  File "/home/franco/Desktop/Proyecto/Codigo/analisis_mas_range_relections.py", line 59, in _selections_changed
    selections = event["selections"]
TypeError: 'bool' object has no attribute '__getitem__'
Exception occurred in traits notification handler for object:  <chaco.array_data_source.ArrayDataSource object at 0x66a94d0>, trait: metadata_changed, old  value: <undefined>, new value: True
#the error continue but is the same error change the selection_masks....
TypeError: 'bool' object has no attribute '__getitem__'
Exception occurred in traits notification handler for object:  <chaco.array_data_source.ArrayDataSource object at 0x6758290>, trait: metadata_changed, old  value: <undefined>, new value: {'selection_masks': (-0.5953709619238516, 10.991581102204394)}
#the selection_masks are the point to I need

感谢

Answer 1

我不确定第一个回溯来自哪里，因为它似乎引用了没有发布在这里的代码。然而，第二次回溯是清楚的。

metadata_changed Event没有被分配元数据的字典。至少，并非总是如此。多年来，修改元数据的工具编写不一致。只需直接从数据源获取元数据字典即可。