基于以下代码示例,我想从CustomJS函数中提取数据(例如x值)以将其保存在python列表
rect_data
中。虽然变量x与ColumnDataSource对象source
同步,但是当我在执行以下代码的图形中绘制矩形选择时,python列表rect_data
仍然为空列表。我做错了什么,如何解决这个问题?谢谢!# You must first run "bokeh serve" to view this example
from bokeh.models import CustomJS, ColumnDataSource, BoxSelectTool, Range1d, Rect
from bokeh.plotting import figure, show
from bokeh.client import push_session
from bokeh.io import curdoc
source = ColumnDataSource(data=dict(x=[], y=[], width=[], height=[]))
callback = CustomJS(args=dict(source=source), code="""
var data = source.get('data');
var geometry = cb_data['geometry'];
var width = geometry['x1'] - geometry['x0'];
var height = geometry['y1'] - geometry['y0'];
var x = geometry['x0'] + width/2;
var y = geometry['y0'] + height/2;
data['x'].push(x);
data['y'].push(y);
data['width'].push(width);
data['height'].push(height);
source.trigger('change');
""")
box_select = BoxSelectTool(callback=callback)
p = figure(plot_width=400,
plot_height=400,
tools=[box_select],
title="Select Below",
x_range=Range1d(start=0.0, end=1.0),
y_range=Range1d(start=0.0, end=1.0))
rect = Rect(x='x',
y='y',
width='width',
height='height',
fill_alpha=0.3,
fill_color='#009933')
p.add_glyph(source, rect, selection_glyph=rect, nonselection_glyph=rect)
session = push_session(curdoc())
def update():
global rect_data
global source
rect_data = source.data['x']
print(rect_data)
curdoc().add_periodic_callback(update,10)
session.show()
session.loop_until_closed()