您可以使用 HoverTool 和 CustomJS,如下面的代码示例所示。此示例绘制从光标位置到 (1,1) 点的直线。打开 JavaScript 控制台时,您可以在移动鼠标时看到 x 和 y 的值。
from bokeh.plotting import figure,show, ColumnDataSource
from bokeh.models import CustomJS, HoverTool
import numpy as np
s = ColumnDataSource(data = dict(x=[0,1],y=[0,1])) #points of the line
callback = CustomJS(args=dict(s=s), code="""
var geometry = cb_data['geometry'];
var x_data = geometry.x; // current mouse x position in plot coordinates
var y_data = geometry.y; // current mouse y position in plot coordinates
console.log("(x,y)=" + x_data+","+y_data); //monitors values in Javascript console
var x = s.get('data')['x'];
var y = s.get('data')['y'];
x[0] = x_data;
y[0] = y_data;
s.trigger('change');
""")
hover_tool = HoverTool(callback=callback)
p = figure(x_range=(0,1), y_range=(0,1), tools= [hover_tool,
"crosshair,box_zoom,wheel_zoom,pan,reset"])
p.line(x='x',y='y',source=s)
show(p)
JavaScript 控制台的输出:
...
VM615:7 (x,y)=0.37494791666666666,0.37447916666666664
VM615:7 (x,y)=0.37494791666666666,0.37114583333333334
VM615:7 (x,y)=0.37161458333333336,0.37114583333333334
VM615:7 (x,y)=0.38828125,0.37114583333333334
VM615:7 (x,y)=0.43161458333333336,0.3878125
VM615:7 (x,y)=0.7216145833333333,0.4878125
...