Using Dictionaries for Customizing Scale’ Breaks, Labels and Values

breaks and lables arguments in scale_xxx() function family each accepts list of values for customizing the scale breaks or labels.

However, it is often more convenient to use a dictionary of breaks (in the labels parameter) or a dictionary of labels (in the breaks parameter) for the breaks/labels customization.

Similar situation is with parameters breaks and values in the scale_xxx_manual() function family.

import pandas as pd

from lets_plot import *

LetsPlot.setup_html()

mpg_df = pd.read_csv ("https://raw.githubusercontent.com/JetBrains/lets-plot-docs/master/data/mpg.csv")
mpg_df.head(3)

	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

p = ggplot(mpg_df, aes(x='displ', y='hwy', color='drv')) + geom_point() 
p

1. Customize the Legend’ Labels

p = p + scale_color_discrete(labels={
    'f': 'front',
    'r': 'rear',
    '4': '4WD'    
})
p

2. Customize the X-Axis breaks and labels

p = p + scale_x_continuous(breaks={
    'min': 1.6,
    '3.4': 3.4,
    '5.2': 5.2,
    'max': 7
})
p

3. Manually Reassign Colors

p + scale_color_manual(values={ 
    'f': 'dark_blue', 
    'r': 'dark_green',
    '4': 'dark_magenta'
})