Draw geom_segments within a circular axis in R

Question

I would need help in order to draw a complex plot with geom_segments along a circular figure.

I have a dataframe such as

  Seq start end
1  S1 61.25   5
2  S2 30.00  35
3  S3 40.00  45
4  S4 52.50   0

And I would like to create a figure such as :

Where I plot each bar coordinates within around the circular axis.

There is no preference about the order of the bars within the y axis.

Here is the dataframe in dput format if it can helps

structure(list(Seq = c("S1", "S2", "S3", "S4"), start = c(61.25, 
30, 40, 52.5), end = c(5L, 35L, 45L, 0L)), class = "data.frame", row.names = c(NA, 
-4L))

user_2835261 · Answer

This gets you pretty close. You may want to tweak the angle values in geom_text() to get it closer.

library(tidyr)
library(dplyr)
library(ggplot2)

text_labs <- df %>%
  select(start, end) %>%
  unlist() %>%
  c(., 17.5) %>%
  sort() %>%
  unique() %>%
  tibble(x = ., y = 70)

df %>%
  mutate(flag = (end < start & end != 0) + 1) %>%
  uncount(flag, .remove = FALSE) %>%
  group_by(Seq) %>%
  mutate(start = case_when(row_number() == 2 ~ 0,
                           TRUE ~ start),
         end = case_when(row_number() == 1 & n() == 2 ~ 70L,
                         end == 0 ~ 70L,
                         TRUE ~ end)) %>%
  mutate(y = cur_group_id() * 5 + 77.5) %>%
  ungroup() %>%
  add_row(start = 0, end = 70, y = 77.5) %>%
  ggplot(aes(y = y, x = start)) +
  geom_segment(aes(yend = y, xend = end), size = 2) +
  geom_hline(yintercept = seq(80, 100, by = 5), colour = "grey90", size = 0.2) +
  geom_text(aes(x, y, label = x), data = text_labs) +
  scale_x_continuous(limits = c(0, 70), breaks = NULL) +
  scale_y_continuous(limits = c(0, 100), labels = NULL) +
  theme_minimal() +
  labs(x = NULL, y = NULL) +
  coord_polar() +
  theme(axis.line.x = element_blank(),
        panel.grid = element_blank())

user_12500315 · Answer

This gets you very close, using geom_textpath:

library(dplyr)
library(geomtextpath)

df %>% 
  group_by(Seq) %>%
  summarize(start = if(start[1] > end[1]) c(start[1], 0) else start[1],
            end = if(start[1] > end[1]) c(70, end[1]) else end[1]) %>%
  ggplot(aes(start, as.numeric(factor(Seq)))) + 
  geom_segment(aes(xend = end, yend = as.numeric(factor(Seq))), size = 1.5) +
  geom_hline(yintercept = seq(0, 4) + 0.5, col = 'gray80') +
  geom_hline(yintercept = 0.5) +
  geom_textpath(data = data.frame(x = unique(c(df$start, df$end, 17.5)), y = -1),
                aes(x, y, label = x), size = 6) +
  scale_y_continuous(limits = c(-10, 5)) +
  scale_x_continuous(limits = c(0, 70)) +
  coord_polar() +
  theme_void()

Draw geom_segments within a circular axis in R

2 Answers