Customizing the Legend

import pandas as pd

from lets_plot import *

LetsPlot.setup_html()

df = pd.read_csv("https://raw.githubusercontent.com/JetBrains/lets-plot-docs/master/data/mpg.csv")
print(df.shape)
df.head()

(234, 12)

	Unnamed: 0	manufacturer	model	displ	year	cyl	trans	drv	cty	hwy	fl	class
0	1	audi	a4	1.8	1999	4	auto(l5)	f	18	29	p	compact
1	2	audi	a4	1.8	1999	4	manual(m5)	f	21	29	p	compact
2	3	audi	a4	2.0	2008	4	manual(m6)	f	20	31	p	compact
3	4	audi	a4	2.0	2008	4	auto(av)	f	21	30	p	compact
4	5	audi	a4	2.8	1999	6	auto(l5)	f	16	26	p	compact

Scale Parameters Related to the Legend

# Default legend
p1 = ggplot(df, aes("cty", "hwy")) + geom_point(aes(color="cyl"))
p1

# Legend name
p1 + scale_color_continuous(name="Number of cylinders")

# Breaks and labels
p1 + scale_color_continuous(breaks=[4, 5, 6, 8], labels=["four", "five", "six", "eight"])

# Format labels
p1 + scale_color_continuous(format="{} cylinders\nin the vehicle’s engine")

Guides

guide_legend()

# Default categorical legend
p2 = ggplot(df, aes("displ", "hwy", color="class")) + geom_point(size=5)
p2

# Legend name
p2 + scale_color_discrete(guide=guide_legend("Vehicle class"))

# Layout the legend in two columns
p2 + scale_color_discrete(guide=guide_legend(ncol=2))

# Fill by rows
p2 + scale_color_discrete(guide=guide_legend(ncol=2, byrow=True))

guide_colorbar()

# Default color legend
p3 = ggplot(df, aes("displ", "hwy")) + geom_point(aes(color="cty"))
p3

# Legend name
p3 + scale_color_continuous(guide=guide_colorbar("City mileage"))

# Adjust colorbar size
p3 + scale_color_continuous(guide=guide_colorbar(barwidth=10, barheight=200))

# Fewer bins
p3 + scale_color_continuous(breaks=[13, 22, 31], guide=guide_colorbar(nbin=3))

guides()

# Default complex legend
p4 = ggplot(df, aes("displ", "hwy")) + geom_point(aes(color="cty", shape="drv"), size=5)
p4

# Guides for 'color' and 'shape' aesthetics
p4 + guides(color=guide_colorbar(barwidth=10), shape=guide_legend(ncol=2))

Customizing Aesthetics Appearance with override_aes

p4 + guides(shape=guide_legend(override_aes={'size': 8, 'color': "#f03b20"}))