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Radar Charts

Source: vignettes/radar.Rmd
radar.Rmd

Overview

Radar charts compare multiple quantitative variables for one or more groups. They are ideal for profiling items across a common set of dimensions.

Setup

Compute element counts per film — Characters, Planets, Species and Starships make natural radar dimensions:

film_metrics <- starwars_films |>
  mutate(
    n_characters = lengths(characters),
    n_planets    = lengths(planets),
    n_species    = lengths(species),
    n_starships  = lengths(starships)
  )

Basic Radar Chart

Profile a single film across its four element dimensions:

RadarChart(
  height  = 300,
  series  = list(
    list(
      label = film_metrics$title[1], 
      data = c(
        film_metrics$n_characters[1], film_metrics$n_planets[1],
        film_metrics$n_species[1], film_metrics$n_starships[1]
      )
    )
  ),
  radar   = list(metrics = c("Characters", "Planets", "Species", "Starships"))
)

Multi-series Radar Chart

Overlay multiple films to compare how each is composed across the same dimensions:

RadarChart(
  height = 350,
  series = list(
    list(
      label = film_metrics$title[1],
      data = c(
        film_metrics$n_characters[1], film_metrics$n_planets[1],
        film_metrics$n_species[1], film_metrics$n_starships[1]
      )
    ),
    list(
      label = film_metrics$title[2],
      data = c(
        film_metrics$n_characters[2], film_metrics$n_planets[2],
        film_metrics$n_species[2], film_metrics$n_starships[2]
      )
    ),
    list(
      label = film_metrics$title[3],
      data = c(
        film_metrics$n_characters[3], film_metrics$n_planets[3],
        film_metrics$n_species[3], film_metrics$n_starships[3]
      )
    )
  ),
  radar  = list(metrics = c("Characters", "Planets", "Species", "Starships"))
)

Series Options

Use fillArea = TRUE to shade the polygon and hideMark = TRUE to suppress vertex dots:

RadarChart(
  height = 350,
  series = list(
    list(
      label = film_metrics$title[1],
      data = c(
        film_metrics$n_characters[1], film_metrics$n_planets[1],
        film_metrics$n_species[1], film_metrics$n_starships[1]
      ),
      fillArea = TRUE
    ),
    list(
      label = film_metrics$title[2],
      data = c(
        film_metrics$n_characters[2], film_metrics$n_planets[2],
        film_metrics$n_species[2], film_metrics$n_starships[2]
      ),
      hideMark = TRUE
    )
  ),
  radar  = list(metrics = c("Characters", "Planets", "Species", "Starships"))
)

Metrics with Fixed Range

Define min and max per metric to ensure all axes share the same scale:

RadarChart(
  height = 350,
  series = list(
    list(
      label = film_metrics$title[1],
      data = c(
        film_metrics$n_characters[1], film_metrics$n_planets[1],
        film_metrics$n_species[1], film_metrics$n_starships[1]
      )
    ),
    list(
      label = film_metrics$title[2],
      data = c(
        film_metrics$n_characters[2], film_metrics$n_planets[2],
        film_metrics$n_species[2], film_metrics$n_starships[2]
      )
    )
  ),
  radar  = list(metrics = list(
    list(name = "Characters", min = 0, max = 20),
    list(name = "Planets",    min = 0, max = 20),
    list(name = "Species",    min = 0, max = 20),
    list(name = "Starships",  min = 0, max = 20)
  ))
)

Grid Shape

Switch between a circular ("circular") and a polygon ("sharp") grid:

RadarChart(
  height    = 350,
  series = list(
    list(
      label = film_metrics$title[1],
      data = c(
        film_metrics$n_characters[1], film_metrics$n_planets[1],
        film_metrics$n_species[1], film_metrics$n_starships[1]
      )
    ),
    list(
      label = film_metrics$title[2],
      data = c(
        film_metrics$n_characters[2], film_metrics$n_planets[2],
        film_metrics$n_species[2], film_metrics$n_starships[2]
      )
    )
  ),
  shape = "circular",
  divisions = 3,
  radar = list(metrics = c("Characters", "Planets", "Species", "Starships"))
)

Highlight

Control hover highlighting with highlight:

RadarChart(
  height    = 350,
  series = list(
    list(
      label = film_metrics$title[1],
      data = c(
        film_metrics$n_characters[1], film_metrics$n_planets[1],
        film_metrics$n_species[1], film_metrics$n_starships[1]
      )
    ),
    list(
      label = film_metrics$title[2],
      data = c(
        film_metrics$n_characters[2], film_metrics$n_planets[2],
        film_metrics$n_species[2], film_metrics$n_starships[2]
      )
    )
  ),
  highlight = "series",
  radar     = list(metrics = c("Characters", "Planets", "Species", "Starships"))
)

Tooltip

Customize tooltip behavior with the trigger option:

RadarChart(
  height    = 350,
  series = list(
    list(
      label = film_metrics$title[1],
      data = c(
        film_metrics$n_characters[1], film_metrics$n_planets[1],
        film_metrics$n_species[1], film_metrics$n_starships[1]
      )
    ),
    list(
      label = film_metrics$title[2],
      data = c(
        film_metrics$n_characters[2], film_metrics$n_planets[2],
        film_metrics$n_species[2], film_metrics$n_starships[2]
      )
    )
  ),
  radar     = list(metrics = c("Characters", "Planets", "Species", "Starships")),
  slotProps = list(tooltip = list(trigger = "axis"))
)

Radar Composition

RadarDataProvider is the dedicated data provider for radar charts. Use it with RadarGrid, RadarAxis, RadarSeriesPlot, and RadarMetricLabels for a fully custom layout:

RadarDataProvider(
  height = 350,
  series = list(
    list(
      label = film_metrics$title[1],
      data = c(
        film_metrics$n_characters[1], film_metrics$n_planets[1],
        film_metrics$n_species[1], film_metrics$n_starships[1]
      )
    ),
    list(
      label = film_metrics$title[2],
      data = c(
        film_metrics$n_characters[2], film_metrics$n_planets[2],
        film_metrics$n_species[2], film_metrics$n_starships[2]
      )
    )
  ),
  radar  = list(metrics = c("Characters", "Planets", "Species", "Starships")),
  ChartsLegend(),
  ChartsTooltip(),
  ChartsSurface(
    RadarGrid(),
    RadarSeriesPlot(),
    RadarAxis(),
    RadarMetricLabels()
  )
)

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