Python，Bokeh：如何更改日期时间轴的范围

我想使用按钮设置日期时间轴的范围。然而，该命令

f.x_range = Range1d(start=start_date, end=end_date)

不起作用。单击按钮时，什么也不会发生。无论是在运行Bokeh服务器的终端窗口中，还是在Chrome web浏览器的控制台输出中，我都没有收到任何错误

您可以在下面找到完整的代码。我很感激你的建议

谢谢

朱利安

# Import libraries
from bokeh.io import curdoc
from bokeh.models import ColumnDataSource, DatetimeTickFormatter, Select, Range1d
from bokeh.models.widgets import Button
from bokeh.layouts import layout
from bokeh.plotting import figure
from datetime import datetime, timedelta
from math import radians


# Create figure
f=figure(x_axis_type='datetime')

# Create sample datetime data
date_time = [datetime(2017,1,1) + timedelta(days=x) for x in range(0,365)]

# Create ColumnDataSource
source = ColumnDataSource(dict(datetime=date_time,parameter=range(0,365)))

# Create Line
f.line(x='datetime',y='parameter',color='olive',line_color='black',source=source)

# Update xaxis function
def update_xaxis():
    start_date = datetime(year=int(select_start_year.value), month=int(select_start_month.value), day=int(select_start_day.value))
    end_date   = datetime(year=int(select_end_year.value), month=int(select_end_month.value), day=int(select_end_day.value))    
    f.x_range = Range1d(start=start_date, end=end_date)

# Set date format for x axis
f.xaxis.formatter=DatetimeTickFormatter(formats=dict(
    seconds=["%Y-%m-%d %H:%M:%S"],
    minsec=["%Y-%m-%d %H:%M:%S"],
    minutes=["%Y-%m-%d %H:%M:%S"],
    hourmin=["%Y-%m-%d %H:%M:%S"],
    hours=["%Y-%m-%d %H:%M:%S"],
    days=["%Y-%m-%d %H:%M:%S"],
    months=["%Y-%m-%d %H:%M:%S"],
    years=["%Y-%m-%d %H:%M:%S"],
    ))
f.xaxis.major_label_orientation=radians(90)

# Create Select and Button widgets
options=[("2015","2015"),("2016","2016"),("2017","2017")]
select_start_year=Select(title="Start Year",value="2017",options=options)
options=[("01","01"),("02","02"),("03","03"),("04","04"),("05","05"),("06","06"),("07","07"),("08","08"),("09","09"),("10","10"),("11","11"),("12","12")]
select_start_month=Select(title="Start Month",value="01",options=options)
options=[("01","01"),("02","02"),("03","03"),("04","04"),("05","05"),("06","06"),("07","07"),("08","08"),("09","09"),("10","10"),("11","11"),("12","12"),("13","13"),("14","14"),("15","15"),("16","16"),("17","17"),("18","18"),("19","19"),("20","20"),("21","21"),("22","22"),("23","23"),("24","25"),("25","26"),("27","27"),("28","28"),("29","29"),("30","30"),("31","31")]
select_start_day=Select(title="Start Day",value="01",options=options)
options=[("2015","2015"),("2016","2016"),("2017","2017")]
select_end_year=Select(title="End Year",value="2017",options=options)
options=[("01","01"),("02","02"),("03","03"),("04","04"),("05","05"),("06","06"),("07","07"),("08","08"),("09","09"),("10","10"),("11","11"),("12","12")]
select_end_month=Select(title="End Month",value="06",options=options)
options=[("01","01"),("02","02"),("03","03"),("04","04"),("05","05"),("06","06"),("07","07"),("08","08"),("09","09"),("10","10"),("11","11"),("12","12"),("13","13"),("14","14"),("15","15"),("16","16"),("17","17"),("18","18"),("19","19"),("20","20"),("21","21"),("22","22"),("23","23"),("24","25"),("25","26"),("27","27"),("28","28"),("29","29"),("30","30"),("31","31")]
select_end_day=Select(title="End Day",value="01",options=options)
button = Button(label='Set Date')

# Update x axis range on click
button.on_click(update_xaxis)

# Add elements to curdoc 
lay_out=layout([[f],[select_start_year],[select_start_month],[select_start_day],[select_end_year],[select_end_month],[select_end_day],[button]])
curdoc().add_root(lay_out)

---

我想出了解决办法。首先，我使用了Datepicker小部件，它比三个Select小部件优雅得多。然后，您必须将DatePicker中的datetime值转换为浮点/整数值，它表示参考日期（即1970年1月1日）经过的秒数。Unix以秒为单位计算，Java脚本需要以毫秒为单位的值，因此乘以1000。代码如下：

# Import libraries
from bokeh.io import curdoc
from bokeh.models import ColumnDataSource, DatetimeTickFormatter, DatePicker
from bokeh.models.widgets import Button
from bokeh.layouts import layout, column, row
from bokeh.plotting import figure
from datetime import datetime, timedelta
from math import radians


# Create figure
f=figure(x_axis_type='datetime')

# Create sample datetime data
date_time = [datetime(2017,1,1) + timedelta(days=x) for x in range(0,365)]

# Create ColumnDataSource
source = ColumnDataSource(dict(datetime=date_time,parameter=range(0,365)))

# Create Line
f.line(x='datetime',y='parameter',color='olive',line_color='black',source=source)

# Update xaxis function
def update_xaxis():
    # Calculate time delta from reference time in seconds
    timestamp_start = (datetime.combine(datepicker_start.value, datetime.min.time())
                        - datetime(1970, 1, 1)) / timedelta(seconds=1)
    timestamp_end = (datetime.combine(datepicker_end.value, datetime.min.time())
                        - datetime(1970, 1, 1)) / timedelta(seconds=1)
    f.x_range.start = int(timestamp_start)*1e3  # Multiply by 1e3 as JS timestamp is in milliseconds
    f.x_range.end   = int(timestamp_end)*1e3  # Multiply by 1e3 as JS timestamp is in milliseconds

# Set date format for x axis
f.xaxis.formatter=DatetimeTickFormatter(formats=dict(
    seconds=["%Y-%m-%d %H:%M:%S"],
    minsec=["%Y-%m-%d %H:%M:%S"],
    minutes=["%Y-%m-%d %H:%M:%S"],
    hourmin=["%Y-%m-%d %H:%M:%S"],
    hours=["%Y-%m-%d %H:%M:%S"],
    days=["%Y-%m-%d %H:%M:%S"],
    months=["%Y-%m-%d %H:%M:%S"],
    years=["%Y-%m-%d %H:%M:%S"],
    ))
f.xaxis.major_label_orientation=radians(90)

# Create Datepicker and Button widgets
datepicker_start = DatePicker(title='Start Date')
datepicker_end = DatePicker(title='End Date')
button = Button(label='Set Date')

# Update x axis range on click
button.on_click(update_xaxis)

# Add elements to curdoc 
lay_out=layout([[row(f,
                     column(button,
                            row(datepicker_start,datepicker_end)))]])
curdoc().add_root(lay_out)