Radial bar chart

The chart we are set to recreate, originally obtained from 1 dataset 100 visualizations website created by Ferdio.

ORIGINAL CHART: #79 stacked radial bar chart

A radial bar chart is essentially a bar chart plotted on a polar coordinates system, rather than on a Cartesian one. In our case, the data visualization is a stacked radial bar chart where categories are stacked on top of each other within each radial segment.

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STORY: UNESCO heritage sites of Scandinavian countries

The #79 data visualization on Ferdio’s website is generated from a single dataset detailing the numbers of UNESCO World Heritage Sites in Scandinavian countries (Sweden, Denmark, and Norway) inscribed before and after 2004, extending up to 2022.

According to properties inscribed on the World Heritage List up to 2022:

Sweden

(https://whc.unesco.org/en/statesparties/se)

Before 2004 (including):

• Royal Domain of Drottningholm (1991)
• Birka and Hovgården (1993)
• Engelsberg Ironworks (1993)
• Rock Carvings in Tanum (1994)
• Skogskyrkogården (1994)
• Hanseatic Town of Visby (1995)
• Church Town of Gammelstad, Luleå (1996)
• Laponian Area (1996)
• Naval Port of Karlskrona (1998)
• Agricultural Landscape of Southern Öland (2000)
• High Coast / Kvarken Archipelago (2000, 2006)
• Mining Area of the Great Copper Mountain in Falun (2001)
• Grimeton Radio Station, Varberg (2004)

After 2004:

• Struve Geodetic Arc (2005)
• Decorated Farmhouses of Hälsingland (2012)

Denmark

(https://whc.unesco.org/en/statesparties/dk)

Before 2004 (including):

• Jelling Mounds, Runic Stones and Church (1994)
• Roskilde Cathedral (1995)
• Kronborg Castle (2000)
• Ilulissat Icefjord (2004)

After 2004:

• Wadden Sea (2009, 2014)
• Stevns Klint (2014)
• Christiansfeld, a Moravian Church Settlement (2015)
• The par force hunting landscape in North Zealand (2015)
• Kujataa Greenland: Norse and Inuit Farming at the Edge of the Ice Cap (2017)
• Aasivissuit – Nipisat. Inuit Hunting Ground between Ice and Sea (2018)

Norway

(https://whc.unesco.org/en/statesparties/no)

Before 2004 (including):

• Bryggen (1979)
• Urnes Stave Church (1979)
• Røros Mining Town and the Circumference (1980, 2010)
• Rock Art of Alta (1985)
• Vegaøyan – The Vega Archipelago (2004)

After 2004:

• West Norwegian Fjords – Geirangerfjord and Nærøyfjord (2005)
• Struve Geodetic Arc (2005)
• Rjukan-Notodden Industrial Heritage Site (2015)

GEOMETRIES

Used geometries

Main geometry:

• geom_segment()

Secondary geometry:

• geom_text()

: STEP-BY-STEP CHART RECREATION

STEP 0: Packages and data preparation

First, we load the necessary packages.

# load packages
library(ggnewscale)
library(tidyverse)

Then we create a dataframe with four columns in R:

df <- tibble(
  x = c(8, 10, 15, 5, 4, 13),
  y = c(1:3, 1:3),
  country = c("Norway", "Denmark", "Sweden", "Norway", "Denmark", "Sweden"),
  group = c("group1", "group1", "group1", "group2", "group2", "group2")
)

x: A numeric variable containing the numbers of UNESCO World Heritage Sites. We use these numbers to define the end of the segments on the x-axis.

y: A numeric variable containing the position of the segment on the y-axis.

country: A character variable containing country names.

group: A character variable containing “group1” and “group2” corresponding to “After 2004” and “Before 2004”, respectively.

We also create two color sets:

# set the colors
cols1 <- c("#F9BBB3", "#7A8092",  "#79B0F6")   # for group1 
cols2 <- c("#EE5440", "#283250", "#3274D8")    # for group2

STEP 1: Create a bar chart with segments for “group1”

We create a simple horizontal bar graph for the “group1” (After 2004) using geom_segment():

df |> 
ggplot() +
  geom_segment(data = filter(df, group == "group1"), 
               aes(x = 0, xend = x, y = y, yend = y, color = country), 
               linewidth = 10, lineend = 'round')

STEP 2: Add labels and set new colors

We add the numbers of UNESCO World Heritage Sites as labels at the end of the bars by incorporating a text-based geometry (geom_text) and we specify a custom color palette by applying the scale_color_manual scale function:

df |> 
ggplot() +
  geom_segment(data = filter(df, group == "group1"), 
               aes(x = 0, xend = x, y = y, yend = y, color = country), 
               linewidth = 10, lineend = 'round') +
  geom_text(data = filter(df, group == "group1"), 
            aes(x, y, label = x), color = "white", size = 6) +
  scale_color_manual(values = cols1)

STEP 3: Add bars, labels and a second color scale for “group2”

df |> 
ggplot() +
  geom_segment(data = filter(df, group == "group1"), 
               aes(x = 0, xend = x, y = y, yend = y, color = country), 
               linewidth = 10, lineend = 'round') +
  geom_text(data = filter(df, group == "group1"), 
            aes(x, y, label = x), color = "white", size = 6) +
  scale_color_manual(values = cols1) +
  new_scale_color() +
  geom_segment(data = filter(df, group == "group2"), 
               aes(x = 0, xend = x, y = y, yend = y, color = country),
               linewidth = 10, lineend = 'round') +
  geom_text(data = filter(df, group == "group2"), 
            aes(x, y, label = x), color = "white", size = 6) +
  scale_color_manual(values = cols2) 

STEP 4: Set legend guides for each scale

df |> 
ggplot() +
  geom_segment(data = filter(df, group == "group1"), 
               aes(x = 0, xend = x, y = y, yend = y, color = country), 
               linewidth = 10, lineend = 'round') +
  geom_text(data = filter(df, group == "group1"), 
            aes(x, y, label = x), color = "white", size = 6) +
  scale_color_manual(values = cols1) +
  guides(color = guide_legend(title = "After 2004")) +
  new_scale_color() +
  geom_segment(data = filter(df, group == "group2"), 
               aes(x = 0, xend = x, y = y, yend = y, color = country),
               linewidth = 10, lineend = 'round') +
  geom_text(data = filter(df, group == "group2"), 
            aes(x, y, label = x), color = "white", size = 6) +
  scale_color_manual(values = cols2) +
  guides(color = guide_legend(title = "Before 2004"))

STEP 5: Switch to the polar coordinate system and change the legend position

df |> 
ggplot() +
  geom_segment(data = filter(df, group == "group1"), 
               aes(x = 0, xend = x, y = y, yend = y, color = country), 
               linewidth = 10, lineend = 'round') +
  geom_text(data = filter(df, group == "group1"), 
            aes(x, y, label = x), color = "white", size = 6) +
  scale_color_manual(values = cols1) +
  guides(color = guide_legend(title = "After 2004")) +
  new_scale_color() +
  geom_segment(data = filter(df, group == "group2"), 
               aes(x = 0, xend = x, y = y, yend = y, color = country),
               linewidth = 10, lineend = 'round') +
  geom_text(data = filter(df, group == "group2"), 
            aes(x, y, label = x), color = "white", size = 6) +
  scale_color_manual(values = cols2) +
  guides(color = guide_legend(title = "Before 2004")) +
  coord_polar() + 
  theme(legend.position = "bottom")

STEP 6: Adjust the limits of the axes

df |> 
ggplot() +
  geom_segment(data = filter(df, group == "group1"), 
               aes(x = 0, xend = x, y = y, yend = y, color = country), 
               linewidth = 10, lineend = 'round') +
  geom_text(data = filter(df, group == "group1"), 
            aes(x, y, label = x), color = "white", size = 6) +
  scale_color_manual(values = cols1) +
  guides(color = guide_legend(title = "After 2004")) +
  new_scale_color() +
  geom_segment(data = filter(df, group == "group2"), 
               aes(x = 0, xend = x, y = y, yend = y, color = country),
               linewidth = 10, lineend = 'round') +
  geom_text(data = filter(df, group == "group2"), 
            aes(x, y, label = x), color = "white", size = 6) +
  scale_color_manual(values = cols2) +
  scale_x_continuous(limits = c(0, 20)) +  
  scale_y_continuous(expand = expansion(mult = 0.3), limits = c(0, 3)) +
  guides(color = guide_legend(title = "Before 2004")) +
  coord_polar() + 
  theme(legend.position = "bottom")

STEP 7: Add country labels

df |> 
ggplot() +
  geom_segment(data = filter(df, group == "group1"), 
               aes(x = 0, xend = x, y = y, yend = y, color = country), 
               linewidth = 10, lineend = 'round') +
  geom_text(data = filter(df, group == "group1"), 
            aes(x, y, label = x), color = "white", size = 6) +
  geom_text(data = filter(df, group == "group1"), 
            aes(x = 0, y, label = country), size = 6, hjust = 1.4) +
  scale_color_manual(values = cols1) +
  guides(color = guide_legend(title = "After 2004")) +
  new_scale_color() +
  geom_segment(data = filter(df, group == "group2"), 
               aes(x = 0, xend = x, y = y, yend = y, color = country),
               linewidth = 10, lineend = 'round') +
  geom_text(data = filter(df, group == "group2"), 
            aes(x, y, label = x), color = "white", size = 6) +
  scale_color_manual(values = cols2) +
  scale_x_continuous(limits = c(0, 20)) +  
  scale_y_continuous(expand = expansion(mult = 0.3), limits = c(0, 3)) +
  guides(color = guide_legend(title = "Before 2004")) +
  coord_polar() +
  theme(legend.position = "bottom")

STEP 8: Fine-tune the chart’s legend

df |> 
ggplot() +
  geom_segment(data = filter(df, group == "group1"), 
               aes(x = 0, xend = x, y = y, yend = y, color = country), 
               linewidth = 10, lineend = 'round') +
  geom_text(data = filter(df, group == "group1"), 
            aes(x, y, label = x), color = "white", size = 6) +
  geom_text(data = filter(df, group == "group1"), 
            aes(x = 0, y, label = country), size = 6, hjust = 1.4) +
  scale_color_manual(values = cols1) +
  guides(color = guide_legend(title = paste0(strrep(" ", 8), "After 2004"),
                              override.aes = list(size = c(3, 4, -2)),
                              reverse = TRUE,
                              keywidth = 1.5, 
                              title.position = "right")) +
  new_scale_color() +
  geom_segment(data = filter(df, group == "group2"), 
               aes(x = 0, xend = x, y = y, yend = y, color = country),
               linewidth = 10, lineend = 'round') +
  geom_text(data = filter(df, group == "group2"), 
            aes(x, y, label = x), color = "white", size = 6) +
  scale_color_manual(values = cols2) +
  scale_x_continuous(limits = c(0, 20)) +  
  scale_y_continuous(expand = expansion(mult = 0.3), limits = c(0, 3)) +
  guides(color = guide_legend(title = paste0(strrep(" ", 8), "Before 2004", strrep(" ", 10)),
                              reverse = TRUE, override.aes = list(size = c(3, 4, -2)),
                              keywidth = 1.5, order = 1,
                              title.position = "right")) +
  coord_polar() +
  theme(legend.position = "bottom",
        legend.title = element_text(size = 14, color = "gray50"),        
        legend.text = element_text(margin = margin(r = -2, unit = 'cm'), color = NA)
  )

STEP 9: Apply final theme adjustments to the chart

df |> 
  ggplot() +
  geom_segment(data = filter(df, group == "group1"), 
               aes(x = 0, xend = x, y = y, yend = y, color = country), 
               linewidth = 10, lineend = 'round') +
  geom_text(data = filter(df, group == "group1"), 
            aes(x, y, label = x), color = "white", size = 6) +
  geom_text(data = filter(df, group == "group1"), 
            aes(x = 0, y, label = country), size = 6, hjust = 1.4) +
  scale_color_manual(values = cols1) +
  guides(color = guide_legend(title = paste0(strrep(" ", 8), "After 2004"),
                              override.aes = list(size = c(3, 4, -2)),
                              reverse = TRUE,
                              keywidth = 1.0, 
                              title.position = "right")) +
  new_scale_color() +
  geom_segment(data = filter(df, group == "group2"), 
               aes(x = 0, xend = x, y = y, yend = y, color = country),
               linewidth = 10, lineend = 'round') +
  geom_text(data = filter(df, group == "group2"), 
            aes(x, y, label = x), color = "white", size = 6) +
  scale_color_manual(values = cols2) +
  scale_x_continuous(limits = c(0, 20)) +  
  scale_y_continuous(expand = expansion(mult = 0.3), limits = c(0, 3)) +
  guides(color = guide_legend(title = paste0(strrep(" ", 8), "Before 2004", strrep(" ", 10)),
                              reverse = TRUE, override.aes = list(size = c(3, 4, -2)),
                              keywidth = 1.0, order = 1,
                              title.position = "right")) +
  coord_polar() +
  theme(panel.background = element_blank(),
        axis.title = element_blank(),
        axis.text = element_blank(),
        axis.ticks = element_blank(),
        legend.position = "bottom",
        legend.title = element_text(size = 14, color = "gray50"),
        legend.text = element_text(margin = margin(r = -2, unit = 'cm'), color = NA),        
        legend.margin = margin(t = -65),
        legend.spacing.x = unit(0.5, "cm"),
        legend.key = element_rect(color = NA, fill = NA)
  )

Storytelling with the chart

In general, the numbers of world heritage sites in Scandinavian countries have increased between 2004 and 2022. Sweden maintained its status as the country with the highest number of UNESCO World Heritage Sites throughout the period, underscoring its rich cultural and natural heritage. However, Denmark emerged as the front runner in terms of acquiring new designations, surpassing both Sweden and Norway in this aspect. Remarkably, Denmark saw a surge in the addition of UNESCO sites, particularly after 2004, contrasting with Sweden and Norway, which garnered most of their designations prior to that year.