Dotplot Geometry

Preparation

import numpy as np
import pandas as pd

from lets_plot import *
from lets_plot.mapping import as_discrete
LetsPlot.setup_html()

DEF_BIN_COUNT = 10

def plot_matrix(plots=[], width=400, height=300, columns=2):
    bunch = GGBunch()
    for i in range(len(plots)):
        row = int(i / columns)
        column = i % columns
        bunch.add_plot(plots[i], column * width, row * height, width, height)
    return bunch.show()

mtcars_df = pd.read_csv("https://gist.githubusercontent.com/seankross/a412dfbd88b3db70b74b/raw/5f23f993cd87c283ce766e7ac6b329ee7cc2e1d1/mtcars.csv")
mtcars_df.head()

	model	mpg	cyl	disp	hp	drat	wt	qsec	vs	am	gear	carb
0	Mazda RX4	21.0	6	160.0	110	3.90	2.620	16.46	0	1	4	4
1	Mazda RX4 Wag	21.0	6	160.0	110	3.90	2.875	17.02	0	1	4	4
2	Datsun 710	22.8	4	108.0	93	3.85	2.320	18.61	1	1	4	1
3	Hornet 4 Drive	21.4	6	258.0	110	3.08	3.215	19.44	1	0	3	1
4	Hornet Sportabout	18.7	8	360.0	175	3.15	3.440	17.02	0	0	3	2

mpg_binwidth = (mtcars_df.mpg.max() - mtcars_df.mpg.min()) / DEF_BIN_COUNT

mpg_df = pd.DataFrame(list(zip(*np.histogram(mtcars_df.mpg, bins=DEF_BIN_COUNT))), columns=["count", "mpg"])
mpg_df['binwidth'] = [mpg_binwidth] * mpg_df.shape[0]
mpg_df.head()

	count	mpg	binwidth
0	2	10.40	2.35
1	4	12.75	2.35
2	6	15.10	2.35
3	6	17.45	2.35
4	5	19.80	2.35

Minimalistic example

ggplot(mtcars_df, aes(x="mpg")) + geom_dotplot() + ggtitle("Simplest example")

Comparison of geoms

PACIFIC_BLUE = '#118ed8'

ggplot(mtcars_df, aes(x="mpg")) + \
    geom_area(stat='density', fill=PACIFIC_BLUE) + \
    geom_dotplot(binwidth=mpg_binwidth, color=PACIFIC_BLUE, fill='white') + \
    ggtitle("density + dotplot")

ggplot(mtcars_df, aes(x="mpg")) + \
    geom_histogram(binwidth=mpg_binwidth, color='white') + \
    geom_dotplot(binwidth=mpg_binwidth, method='histodot', color=PACIFIC_BLUE, fill='white') + \
    coord_fixed(ratio=mpg_binwidth) + \
    ggtitle("histogram + dotplot")

Parameters

stackdir

p = ggplot(mtcars_df, aes(x="mpg"))
p1 = p + geom_dotplot(binwidth=mpg_binwidth, stackdir='up') + ggtitle("stackdir='up' (default)")
p2 = p + geom_dotplot(binwidth=mpg_binwidth, stackdir='down') + ggtitle("stackdir='down'")
p3 = p + geom_dotplot(binwidth=mpg_binwidth, stackdir='center') + ggtitle("stackdir='center'")
p4 = p + geom_dotplot(binwidth=mpg_binwidth, stackdir='centerwhole') + ggtitle("stackdir='centerwhole'")

plot_matrix([p1, p2, p3, p4])

stackratio

p = ggplot(mtcars_df, aes(x="mpg"))
p1 = p + geom_dotplot(binwidth=mpg_binwidth, stackratio=1.0) + ggtitle("stackratio=1.0 (default)")
p2 = p + geom_dotplot(binwidth=mpg_binwidth, stackratio=0.5) + ggtitle("stackratio=0.5")
p3 = p + geom_dotplot(binwidth=mpg_binwidth, stackratio=1.5) + ggtitle("stackratio=1.5")

plot_matrix([p1, p2, p3])

dotsize

p = ggplot(mtcars_df, aes(x="mpg"))
p1 = p + geom_dotplot(binwidth=mpg_binwidth, dotsize=1.0) + ggtitle("dotsize=1.0 (default)")
p2 = p + geom_dotplot(binwidth=mpg_binwidth, dotsize=0.5) + ggtitle("dotsize=0.5")
p3 = p + geom_dotplot(binwidth=mpg_binwidth, dotsize=1.5) + ggtitle("dotsize=1.5")

plot_matrix([p1, p2, p3])

center

p = ggplot(mtcars_df, aes(x="mpg"))
p1 = p + geom_dotplot(binwidth=mpg_binwidth, method='histodot') + ggtitle("Default")
p2 = p + geom_dotplot(binwidth=mpg_binwidth, method='histodot', center=11.0) + ggtitle("center=11.0")

plot_matrix([p1, p2])

boundary

p = ggplot(mtcars_df, aes(x="mpg"))
p1 = p + geom_dotplot(binwidth=mpg_binwidth, method='histodot') + ggtitle("Default")
p2 = p + geom_dotplot(binwidth=mpg_binwidth, method='histodot', boundary=10.0) + ggtitle("boundary=10.0")

plot_matrix([p1, p2])

bins

p = ggplot(mtcars_df, aes(x="mpg"))
p1 = p + geom_dotplot(method='histodot') + ggtitle("Default")
p2 = p + geom_dotplot(method='histodot', bins=20) + ggtitle("bins=20")

plot_matrix([p1, p2])

Grouping

ggplot(mtcars_df, aes(x="mpg")) + \
    geom_dotplot(aes(fill=as_discrete("cyl")), \
                 binwidth=mpg_binwidth, color='black') + \
    ggtitle("method='dotdensity'")

p = ggplot(mtcars_df, aes(x="mpg"))
p1 = p + geom_dotplot(aes(fill=as_discrete("cyl")), method='histodot', \
                      binwidth=mpg_binwidth, color='black') + \
    ggtitle("method='histodot' (default)")
p2 = p + geom_dotplot(aes(fill=as_discrete("cyl")), method='histodot', \
                      binwidth=mpg_binwidth, stackgroups=True, color='black') + \
    ggtitle("method='histodot' and stackgroups=True")

plot_matrix([p1, p2])

Tooltips

ggplot(mtcars_df, aes(x="mpg")) + \
    geom_dotplot(binwidth=mpg_binwidth, \
                 tooltips=layer_tooltips().line("Stack center|^x")\
                                          .line("Number of dots in stack|@..count..")\
                                          .line("Dot diameter|@..binwidth..")) + \
    ggtitle("With tooltips")

Facetting

ggplot(mtcars_df, aes(x="mpg")) + \
    geom_dotplot(aes(fill=as_discrete("cyl")), \
                 binwidth=mpg_binwidth, color='black') + \
    facet_grid(x="cyl") + \
    ggtitle("facet_grid()")

Coordinates

Fixed

ggplot(mtcars_df, aes(x="mpg")) + \
    geom_dotplot(binwidth=mpg_binwidth) + \
    coord_fixed(ratio=mpg_binwidth) + \
    ggtitle("Fixed coordinates")

Flip

ggplot(mtcars_df, aes(x="mpg")) + \
    geom_dotplot(binwidth=mpg_binwidth) + \
    coord_flip() + \
    ggtitle("Flip coordinates")

"identity" statistic

ggplot(mpg_df, aes(x="mpg", stacksize="count", binwidth="binwidth")) + \
    geom_dotplot(stat='identity') + \
    ggtitle("stat='identity'")

Additional layers

ggplot(mtcars_df, aes(x="mpg")) + \
    geom_dotplot(aes(fill=as_discrete("vs")), method='histodot', \
                 bins=9, stackdir='center', \
                 stackratio=0.8, dotsize=0.8, \
                 color='black', alpha=.5, size=1) + \
    scale_fill_brewer(type='qual', palette='Set1') + \
    theme_grey() + \
    ggtitle("Some additional aesthetics, parameters and layers")