legends

This example shows different ways to place legends on a graph using the different location values included in the enumeration LegendLocation. The legend can be defined in terms of title, shape and orientation. This graph shows sin and cos plots.

Details

Bokeh APIs:

bokeh.core.enums.LegendLocation, bokeh.models.ColumnDataSource, bokeh.models.DataRange1d, bokeh.models.Plot, bokeh.models.Legend

More info:

Styling legends

Keywords:

sin, cos, pi, linspace, LegendLocation

from numpy import cos, linspace, pi, sin

from bokeh.core.enums import LegendLocation
from bokeh.io import show
from bokeh.models import (ColumnDataSource, DataRange1d, Legend, Line, LinearAxis,
                          PanTool, Plot, SaveTool, Scatter, WheelZoomTool)

x = linspace(-2*pi, 2*pi, 400)
y = sin(x)
y2 = cos(x)

source = ColumnDataSource(data=dict(x=x, y=y, y2=y2))

xdr = DataRange1d()
ydr = DataRange1d()

plot = Plot(
    x_range=xdr,
    y_range=ydr,
    width=1000,
    height=1000,
    min_border=0,
    toolbar_location=None,
    background_fill_color="#F0F0F0",
    border_fill_color="lightgray",
)

line_glyph = Line(x="x", y="y", line_color="navy", line_width=2, line_dash="dashed")
line = plot.add_glyph(source, line_glyph)
circle = Scatter(x="x", y="y2", size=6, line_color="red", fill_color="orange", fill_alpha=0.6)
circle = plot.add_glyph(source, circle)

pan = PanTool()
wheel_zoom = WheelZoomTool()
preview_save = SaveTool()

plot.add_tools(pan, wheel_zoom, preview_save)

# Add axes (Note it's important to add these before adding legends in side panels)
plot.add_layout(LinearAxis(), "below")
plot.add_layout(LinearAxis(), "left")
plot.add_layout(LinearAxis(), "right")

def add_legend(location, orientation, side, background_fill_color="#FFFFFF"):
    legend = Legend(
        items=[("line", [line]), ("circle", [circle])],
        location=location,
        orientation=orientation,
        border_line_color="black",
        background_fill_color=background_fill_color,
        title=f"Legend at\n{location!r}\n{orientation!r}\n{side!r}",
    )
    plot.add_layout(legend, side)

# Add legends in names positions e.g. "top_right", "top_left" (see plot for all)
for location in LegendLocation:
    # redundant positions get a different background color and a vertical orientation to show ambiguity
    if "_" not in location:
        background_fill_color = "#999999"
        orientation = "vertical"
    else:
        background_fill_color ="#CCCCCC"
        orientation = "horizontal"
    add_legend(location, orientation, "center", background_fill_color=background_fill_color)

# Add legend at fixed positions
add_legend((150, 50), "horizontal", "center")

# Add legend in side panels
add_legend("center_left", "horizontal", "above")
add_legend("center", "horizontal", "below")
add_legend("center", "vertical", "left")
add_legend("bottom_center", "vertical", "right")

show(plot)