Bokeh: Vbar cannot be shown for datetime xaxis

Question

I prepared two ColumnDataSource which has different data set for y axis.

    plot.line('x', 'y', source=source, line_width=2)
    plot.circle('x', 'y', source=source, fill_color="blue", size=8)
    plot.vbar(x='x', top='y', source=source1, width=0.5, bottom=0, fill_color="red")#this part doesn't work.

And line and circle does work but when I tried to show the vbar for another data, it doesn't show but seems like the range of the axis is changed by the vbar codes.

I tried to show only the vbar graph on mini program. And vber is never shown for my dataframe.

And I found out there's a problem with my datetime object. The line graph can be shown for datetime object's xaxis. But I changed the code for showing vbar, it doesn't show anything. And when I changed the xaxis to just the number, like x=[1, 2, 3...] while top keeps the same, the vbar is shown.

Vbar cannot be used for datetime? Or is there another reason? I'm sure the datetime xaxis is the problem.

Answer 1

Datetime axes are ultimately denominated in units of "milliseconds since epoch". For vbars to show up on a datetime axis, you will usually have to make the width much larger (0.5 means 0.5 milliseconds which is just going to be invisible at most typical scales)