使用“散景服务”动态添加/删除情节。 （散景0.12.0）

Question

我的问题与使用散景0.7.1的another thread非常相似，但散景服务器的API在0.12.0中已经发生了足够的变化，我正在努力使这个答案适应新版本。

总而言之，我有一个页面，其中包含一个时间流网格图，从不断更新的文件中提取数据。该页面有一个MultiSelect菜单，列出了我文件中的所有变量。我希望能够在菜单中选择不同的变量，按一个按钮，然后让现有变量的图消失并替换为新的时间流，其中图的数量可能不同。我正在使用bokeh serve --show script.py包装器运行我的脚本。

在我最初的尝试中，我为一个按钮分配了一个事件处理程序，它清除了“curdoc”。然后从MultiSelect中添加新选择的变量的图。这会运行，但图表的数量不会更新。显然，我错过了告诉服务器以某种方式刷新页面布局的调用。

import numpy as np

from bokeh.driving import count
from bokeh.plotting import figure, curdoc
from bokeh.layouts import gridplot
from bokeh.models import Slider, Column, Row, ColumnDataSource, MultiSelect, Button
from netCDF4 import Dataset
import datetime

# data
#data = Dataset('/daq/spt3g_software/dfmux/bin/output.nc', 'r', format='NETCDF4')
data = Dataset('20160714_warm_overbiased_noise.nc', 'r', format='NETCDF4')
vars = data.variables.keys()[1:11]

# plots
d = {('y_%s'%name):[] for name in vars}
d['t'] = []
source = ColumnDataSource(data=d)

figs = [figure(x_axis_type="datetime", title=name) for name in vars]
plots = [f.line(x='t', y=('y_%s'%f.title.text), source=source, color="navy", line_width=1) for f in figs]
grid = gridplot(figs, ncols=3, plot_width=500, plot_height=250)

# UI definition
npoints = 2000
slider_npoints = Slider(title="# of points", value=npoints, start=1000, end=10000, step=1000.)
detector_select = MultiSelect(title="Timestreams:", value=[], options=vars)
update_detector_button = Button(label="update detectors", button_type="success")

# UI event handlers
def update_detector_handler():
    global figs, plots, grid, source
    d = {('y_%s'%name):[] for name in detector_select.value}
    d['t'] = []
    source = ColumnDataSource(data=d)

    figs = [figure(x_axis_type="datetime", title=name) for name in detector_select.value]
    plots = [f.line(x='t', y=('y_%s'%f.title.text), source=source, color="navy", line_width=1) for f in figs]
    grid = gridplot(figs, ncols=3, plot_width=500, plot_height=250)
    curdoc().clear()
    curdoc().add_root(Column(Row(slider_npoints, Column(detector_select, update_detector_button)), grid))

update_detector_button.on_click(update_detector_handler)

# callback updater
@count()
def update(t):
    data = Dataset('20160714_warm_overbiased_noise.nc', 'r', format='NETCDF4')
    #data = Dataset('/daq/spt3g_software/dfmux/bin/output.nc', 'r', format='NETCDF4')

    npoints = int(slider_npoints.value)
    new_data = {('y_%s'%f.title.text):data[f.title.text][-npoints:] for f in figs}
    new_data['t'] = data['Time'][-npoints:]*1e3

    source.stream(new_data, npoints)

# define HTML layout and behavior
curdoc().add_root(Column(Row(slider_npoints, Column(detector_select, update_detector_button)), grid))
curdoc().add_periodic_callback(update, 500)

Answer 1

Bokeh Github页面here回答了类似的问题。

基本上，您可以修改布局对象的子代，而不是弄乱curdoc()。 someLayoutHandle.children。

一个简单的例子是使用切换按钮添加和删除图表：

from bokeh.client import push_session
from bokeh.layouts import column, row
from bokeh.models import Toggle
from bokeh.plotting import figure, curdoc
import numpy as np
# Create an arbitrary figure
p1 = figure(name = 'plot1')

# Create sin and cos data
x = np.linspace(0, 4*np.pi, 100)
y1 = np.sin(x)
y2 = np.cos(x)

# Create two plots
r1 = p1.circle(x,y1)

# Create the toggle button
toggle = Toggle(label = 'Add Graph',active=False)

mainLayout = column(row(toggle,name='Widgets'),p1,name='mainLayout')
curdoc().add_root(mainLayout)
session = push_session(curdoc())
# Callback which either adds or removes a plot depending on whether the toggle is active
def toggleCallback(attr):
    # Get the layout object added to the documents root
    rootLayout = curdoc().get_model_by_name('mainLayout')
    listOfSubLayouts = rootLayout.children

    # Either add or remove the second graph
    if  toggle.active == False:
        plotToRemove = curdoc().get_model_by_name('plot2')
        listOfSubLayouts.remove(plotToRemove)

    if toggle.active == True:
        if not curdoc().get_model_by_name('plot2'):
            p2 = figure(name='plot2')
            plotToAdd = p2
            p2.line(x,y2)
            # print('Remade plot 2')
        else:
            plotToAdd = curdoc().get_model_by_name('plot2')
        listOfSubLayouts.append(plotToAdd)

# Set the callback for the toggle button
toggle.on_click(toggleCallback)

session.show()
session.loop_until_closed()

给我带来最大麻烦的部分是确保我想要添加的图是curdoc()的一部分，这就是定义在回调函数中的原因。如果它不在回调范围内，则每次删除plot2时，bokeh后端都无法找到它。要检查是否是这种情况，请在回调函数中取消注释print语句。

我希望这有帮助！