Creating Magnifier Inset Effect with ggbunch()

The ggbunch() here combines two plots into a single figure with custom layout - a main scatter plot showing diamond price vs. carat weight colored by cut quality, and a zoomed-in inset that magnifies a specific region of interest.

import pandas as pd

from lets_plot import *

LetsPlot.setup_html()

df = pd.read_csv("https://raw.githubusercontent.com/JetBrains/lets-plot-docs/refs/heads/master/data/diamonds.csv")
print(df.shape)
df.head(3)

(53940, 10)

	carat	cut	color	clarity	depth	table	price	x	y	z
0	0.23	Ideal	E	SI2	61.5	55.0	326	3.95	3.98	2.43
1	0.21	Premium	E	SI1	59.8	61.0	326	3.89	3.84	2.31
2	0.23	Good	E	VS1	56.9	65.0	327	4.05	4.07	2.31

# Convert the 'cut' column to categorical data type with specified order
cut_categories = ['Fair', 'Good', 'Very Good', 'Premium', 'Ideal']
df['cut'] = pd.Categorical(df['cut'], categories=cut_categories, ordered=True)

p_base = (ggplot(df, aes("carat", "price", color="cut"))
 + geom_point()
 + geom_smooth(deg=2, size=1, tooltips='none')
 + scale_color_viridis(direction = -1)
)

# The region of interest
carat_min = 2.1
carat_max = 2.7
price_min = 12650
price_max = 17100

# The main plot
p_main = (p_base
 + geom_rect(xmin=carat_min,
             xmax=carat_max,
             ymin=price_min,
             ymax=price_max,
             alpha=0.4, inherit_aes=False, fill='white')
 + theme_grey()
 + coord_cartesian(ylim = [0, 20000])
 + theme(legend_position=[0.58, 0.02], legend_justification=[0, 0])
)

p_main

# The 'magnifier' plot
p_mag = (p_base
 + theme_minimal()
 + coord_cartesian(xlim=[carat_min, carat_max],
                   ylim=[price_min, price_max])
 + theme_void()
 + theme(legend_position='none', plot_inset=0)
)

p_mag

(ggbunch(
    plots = [
        (p_main
          + geom_segment(x=carat_min, y=price_min, xend=4.30, yend=5800, inherit_aes=False, size=0.5)
          + geom_segment(x=carat_min, y=price_max, xend=4.30, yend=19100, inherit_aes=False, size=0.5)
        ),
        p_mag + theme(plot_background=element_rect(size=2, fill='rgba(255, 255, 255, 0.7)'))
    ],
    regions = [
        (0, 0, 0.9, 1),
        (0.75, 0.05, 0.25, 0.6)
    ]
) 
 + ggsize(900, 600)
 + ggtitle('Diamond Price vs. Carat Weight by Cut Quality')
 + theme(plot_title=element_text(hjust=0.5, size=18))
)