散景：线图上的意外（损坏？）缩放行为

Question

我正在使用 Bokeh+tornado 构建实时绘图实用程序，我遇到了一种奇怪的行为，即绘图自动缩放未按预期运行，特别是存在三个令人费解的问题。知道什么地方会出错吗？我可以调查什么？

显示行为的图片问题列表：

线图仅针对正 Y 轴值自动缩放（预期数字显示 -50 到 50 之间的随机值，但问题是 Y 轴不缩放到 0 以下）：

滚动的实时图在特定时刻突然停止跟随数据，疯狂缩放和翻转 X 轴，然后在一段时间后恢复（这总是发生一次，在 t=10，两个图突然改变变成这样，几秒后恢复正常绘图):

线图仅根据一条线自动缩放而忽略其余部分（这里向上的线将被自动缩放“跟随”，这会增加最小 Y，直到其他线不再可见） :

这是重现该行为的代码：

from bokeh.server.server import Server
from bokeh.application import Application
from bokeh.application.handlers.function import FunctionHandler
from bokeh.plotting import figure, ColumnDataSource
from tornado import gen
from tornado.ioloop import IOLoop
from multiprocessing import Process, Pipe


class LivePlotApp(object):
    parent_conn, child_conn = Pipe()

    def __init__(self, data_format, app_name='myapp', update_step_ms=1,
                 stream_rollover=50):
        self.app_name = app_name
        self.data_format = data_format
        self.update_step_ms = update_step_ms
        self.stream_rollover = stream_rollover
        self.figs = []
        self.lines = []
        self.figs_n = 0

    def start_process(self):
        self.process =\
            Process(target=self.start_io_loop,
                    args=(self.child_conn,),
                    daemon=True)
        self.process.start()

    # Safe update
    @gen.coroutine
    def locked_update(self):
        try:
            x = self.cc.recv()  # This is blocking
        except EOFError:
            return
        self.source.stream(x, rollover=self.stream_rollover)

    def start_io_loop(self, child_conn):
        self.io_loop = IOLoop.current()
        self.server = Server(applications={
            '/'+self.app_name: Application(FunctionHandler(self.make_document))
            }, io_loop=self.io_loop, port=5001)
        self.server.start()
        self.server.show('/'+self.app_name)
        self.cc = child_conn
        self.io_loop.start()

    def make_document(self, doc):
        # Define data source
        self.source = ColumnDataSource(self.data_format)

        # Add figures and lines to plots to document
        figs = []
        for f in self.figs:
            fig = figure(**f)
            figs.append(fig)
        for line in self.lines:
            for fig_n, params in line.items():
                figs[fig_n].line(*params[0], **params[1], source=self.source)
        for f in figs:
            doc.add_root(f)
        ###################################################################
        # If you don't need/want to use add_figure, or add_line_to_figure
        # you can just make a fixed layout
        ###################################################################
        # fig1 = figure(title="FIG 1")
        # fig1.line("t", "x", line_color="pink", source=self.source)
        # fig1.line("t", "y", line_color="red", source=self.source)
        # fig1.line("t", "z", line_color="blue", line_width=2,
        #           source=self.source)
        # doc.add_root(fig1)
        # fig2 = figure(title="FIG 2")
        # fig2.line('t', 'other', source=self.source)
        # doc.add_root(fig2)
        ###################################################################

        doc.add_periodic_callback(self.locked_update, self.update_step_ms)

    def add_figure(self, **kwargs):
        self.figs.append(kwargs)
        self.figs_n += 1
        return self.figs_n-1

    def add_line_to_figure(self, f, *args, **kwargs):
        self.lines.append({f: (args, kwargs)})


if __name__ == '__main__':
    # Example usage
    import time
    import random
    import math
    dict_data = {'t': [], 'x': [], 'y': [], 'z': [], 'other': []}
    app = LivePlotApp(data_format=dict_data, app_name="Demo_app")
    f1 = app.add_figure(title="Fig 1", plot_width=300, plot_height=300)
    app.add_line_to_figure(f1, "t", "y", line_color="pink")
    app.add_line_to_figure(f1, "t", "z", line_color="red", line_width=2)
    app.add_line_to_figure(f1, "t", "x", line_color="blue")
    app.add_line_to_figure(f1, "t", "x")
    f2 = app.add_figure(title="Fig 2", plot_width=300, plot_height=300)
    app.add_line_to_figure(f2, "t", "other", line_color="blue")

    app.start_process()
    i = 0
    dt = 0.01  # Send data at 100Hz
    t_sent = time.perf_counter()

    while True:
        time.sleep(0.1)
        t = time.perf_counter()
        dict_data['other'] = [random.randint(-50, 50)]
        dict_data['t'] = [time.perf_counter()],
        dict_data['x'] = [7 if i < 110 else 15]
        dict_data['y'] = [i % 100]
        dict_data['z'] = [10*math.sin(t*2*math.pi)]
        if (t-t_sent > dt):
            t_sent = time.perf_counter()
            app.parent_conn.send(dict_data)
            i += 1

Answer 1

你在这一行中有一个尾随逗号:

dict_data['t'] = [time.perf_counter()],

它创建了一个只有一个列表的元组，并且把事情搞砸了。

散景：线图上的意外（损坏？）缩放行为

Bokeh: Unexpected (broken?) zoom behavior on line plots

python

plot

real-time-data

bokeh