hover_tooltip_formatting

import numpy as np

from bokeh.models import ColumnDataSource, HoverTool
from bokeh.plotting import figure, show
from bokeh.sampledata.stocks import AAPL


def datetime(x):
    return np.array(x, dtype=np.datetime64)

source = ColumnDataSource(data={
    'date'      : datetime(AAPL['date'][::10]),
    'adj close' : AAPL['adj_close'][::10],
    'volume'    : AAPL['volume'][::10],
})

p = figure(height=250, x_axis_type="datetime", tools="", toolbar_location=None,
           title="Hover Tooltip Formatting", sizing_mode="scale_width")
p.background_fill_color="#f5f5f5"
p.grid.grid_line_color="white"
p.xaxis.axis_label = 'Date'
p.yaxis.axis_label = 'Price'
p.axis.axis_line_color = None

p.line(x='date', y='adj close', line_width=2, color='#ebbd5b', source=source)

p.add_tools(HoverTool(
    tooltips=[
        ( 'date',   '@date{%F}'            ),
        ( 'close',  '$@{adj close}{%0.2f}' ), # use @{ } for field names with spaces
        ( 'volume', '@volume{0.00 a}'      ),
    ],

    formatters={
        '@date'        : 'datetime', # use 'datetime' formatter for '@date' field
        '@{adj close}' : 'printf',   # use 'printf' formatter for '@{adj close}' field
                                     # use default 'numeral' formatter for other fields
    },

    # display a tooltip whenever the cursor is vertically in line with a glyph
    mode='vline',
))

show(p)