散景：绘制多条单独的线

Question

ISSUE no.1:

I cant come up with solving the way how to plot multiple separate lines other than this piece:

main_time_line = p.line(x=(start, stop), y=(0, 0))

g1 = p.square(source=source, x='examination__date', y=0, size=4,
              color='black', name='g1')

hover_tool.renderers.append(g1)

g2 = p.circle(source=source, x='examination__date', y='level', size=15)

for i, (idate, ilevel, iname) in enumerate(zip(source.data['examination__date'],
                                               source.data['level'],
                                               source.data['examination__name'])):
    vert = 'top' if ilevel < 0 else 'bottom'
    horizontal = 'right' if ilevel < 0 else 'left'
    yoff = -10 if ilevel < 0 else 10
    p.line(x=idate, y=(0, ilevel), color='black', line_width=3)
    my_txt = Label(x=idate, 
                   y=ilevel, 
                   text=iname, 
                   text_align=horizontal,
                   text_baseline=vert, 
                   text_font_size='13px', 
                   y_offset=yoff)
    p.add_layout(my_txt)

The result of the above is:

The visual effect is more or less what I inteded, however the fact that vertical lines are ploted using for-loop, creates problems with widgets, namely: checkboxes react only to square and circle.

I guess its due to the fact that vert lines are ploted without source arg, therefore emiting changes via JS callback doesnt update data for them (source is a ColumDataSource from pandas dataframe) I wasn't able to plot them the way they are while using source arg.

ISSUE no.2: assuming that i scrap the for-loop, Im unable to operate placement of text

Any suggestions please ?

Answer 1

Further inspection of the documentation led me discovering segments and LabelSets, therefore to achieve the effect i wanted, i only had to add a 'zeroes' list consisting of 0 to ColumnDataSource.

Im sure there are many other ways to handle it tho.

main_time_line = p.line(x=(start, stop), y=(0, 0), color='blue')

g1 = p.square(source=source, x='examination__date', y=0, size=4, 
              color='black', name='g1')

hover_tool.renderers.append(g1)

g2 = p.circle(source=source, x='examination__date', y='level', size=15)

g3 = p.segment(source=source, 
               x0='examination__date', 
               y0='zeroes',
               x1='examination__date', 
               y1='level',
               color="#F4A582", 
               line_width=3)

labels = LabelSet(x='examination__date', y='level', text='examination__name', 
                  level='glyph', x_offset=5, y_offset=5, source=source, 
                  render_mode='canvas')

p.add_layout(labels)