Create a dumbbell chart. — dumbbell

A dumbbell chart (also called a connected dot plot) displays two values per category as dots connected by a horizontal line. It is ideal for showing the change or gap between two groups, time points, or conditions across multiple categories — a clean alternative to grouped bar charts favoured by outlets such as the New York Times and The Economist.

dumbbell_chart(
  data,
  x1,
  x2,
  y,
  x1Label = NULL,
  x2Label = NULL,
  col1 = "steelblue",
  col2 = "crimson",
  lineCol = "#aaaaaa",
  lineWidth = 2,
  circleRadius = 6,
  sort = "none",
  xtitle = NULL,
  xtitleFontSize = 13,
  title = NULL,
  titleFontSize = 16,
  xFontSize = 11,
  yFontSize = 11,
  legend = TRUE,
  legendFontSize = 11,
  font = "Verdana, Geneva, Tahoma, sans-serif",
  bgcol = "white",
  axisCol = "black",
  width = NULL,
  height = NULL
)

Arguments

data: The data frame containing the variables to consider.
x1: The name of the column for the first value (left dot).
x2: The name of the column for the second value (right dot).
y: The name of the categorical column used as row labels.
x1Label: Legend label for the first value. Defaults to the value of x1.
x2Label: Legend label for the second value. Defaults to the value of x2.
col1: Color of the first dot. Defaults to "steelblue".
col2: Color of the second dot. Defaults to "crimson".
lineCol: Color of the line connecting the two dots. Defaults to "#aaaaaa".
lineWidth: Width of the connecting line in pixels. Defaults to 2.
circleRadius: Radius of the dots in pixels. Defaults to 6.
sort: Whether to sort the rows. One of "none" (default), "ascending", or "descending", ordered by the x1 value.
xtitle: Optional. Title of the x-axis.
xtitleFontSize: Font size of the x-axis title. Defaults to 13.
title: Optional. Title of the chart.
titleFontSize: Font size of the chart title. Defaults to 16.
xFontSize: Font size of the x-axis tick labels. Defaults to 11.
yFontSize: Font size of the y-axis category labels. Defaults to 11.
legend: Whether to display a legend. Defaults to TRUE.
legendFontSize: Font size of the legend text. Defaults to 11.
font: The font family used for all text. Defaults to "Verdana, Geneva, Tahoma, sans-serif".
bgcol: Background color of the SVG. Defaults to "white".
axisCol: Color of axis lines, ticks, and labels. Defaults to "black".
width: Optional. The width of the SVG output.
height: Optional. The height of the SVG output.

Value

An SVG dumbbell chart.

Examples

# Life expectancy change between 1952 and 2007 for selected countries
life_exp <- data.frame(
  country = c("Brazil", "China", "Egypt", "India",
              "Japan", "Mexico", "Nigeria", "Turkey"),
  year_1952 = c(50.9, 44.0, 41.9, 37.4, 63.0, 50.8, 36.3, 43.6),
  year_2007 = c(72.4, 72.9, 71.3, 64.7, 82.6, 76.2, 46.9, 71.8)
)

dumbbell_chart(
  data     = life_exp,
  x1       = "year_1952",
  x2       = "year_2007",
  y        = "country",
  x1Label  = "1952",
  x2Label  = "2007",
  title    = "Life expectancy: 1952 vs 2007",
  xtitle   = "Life expectancy (years)",
  sort     = "ascending"
)


# Comparing city vs highway fuel economy by car class
library(ggplot2)
library(dplyr)

mpg_summary <- summarise(group_by(mpg, class),
  city = mean(cty), highway = mean(hwy))

dumbbell_chart(
  data    = mpg_summary,
  x1      = "city",
  x2      = "highway",
  y       = "class",
  x1Label = "City",
  x2Label = "Highway",
  col1    = "steelblue",
  col2    = "darkorange",
  title   = "City vs highway fuel economy by class",
  xtitle  = "Miles per gallon",
  sort    = "ascending"
)