coordonnées polaires

Code R de l'exemple ggplot2

library(ggplot2)
library(patchwork)

## A monthly cycle drawn as an area, as points, as a line and as stacked
## bars, in Cartesian coordinates, then through coord_radial() with either
## axis as the angle. Area, points and line: air temperature at Nottingham,
## 1920-1939, converted from Fahrenheit. Stacked bars: car occupants killed
## or seriously injured in Great Britain, before the seat-belt law of 1983;
## counts add up, which temperatures do not.
monthly <- data.frame(month = as.numeric(cycle(nottem)),
                      temp = (as.numeric(nottem) - 32) * 5 / 9)
mean_temp <- aggregate(temp ~ month, monthly, mean)

seats <- data.frame(month = as.numeric(cycle(Seatbelts)),
                    year = floor(as.numeric(time(Seatbelts))),
                    Seatbelts[, c("drivers", "front", "rear")])
casualties <- aggregate(cbind(drivers, front, rear) ~ month,
                        subset(seats, year < 1983), mean) |>
  reshape(direction = "long", varying = c("drivers", "front", "rear"),
          v.names = "n", timevar = "seat",
          times = c("driver", "front passenger", "rear passenger"))
casualties$seat <- factor(casualties$seat,
                          levels = c("driver", "front passenger", "rear passenger"))

## Plum, blue and orange of the site, set far apart in lightness (grey levels
## 36, 106 and 170) so that the three seats stay apart in grey too. The
## subtitle names them in the same colours, instead of a legend.
seat_colours <- c(driver = "#5a1238", "front passenger" = "#2e7891",
                  "rear passenger" = "#e9a04f")
coloured <- function(label, seat) {
  sprintf("<span style='color:%s'>**%s**</span>", seat_colours[[seat]], label)
}

layers <- list(
  area = geom_area(data = mean_temp, aes(month, temp), fill = "#9b2367", alpha = 0.75),
  point = geom_point(data = monthly, aes(month, temp), colour = "#2e7891",
                     size = 0.5, alpha = 0.6),
  line = geom_line(data = mean_temp, aes(month, temp), colour = "#dc863b", linewidth = 0.8),
  stack = list(geom_col(data = casualties, aes(month, n, fill = seat), width = 0.8),
               scale_fill_manual(values = seat_colours))
)
x_scale <- scale_x_continuous(limits = c(0.5, 12.5), breaks = c(1, 4, 7, 10),
                              expand = c(0, 0))
temp_scale <- scale_y_continuous(limits = c(-1, 20), breaks = c(0, 5, 10, 15),
                                 expand = c(0, 0))
count_scale <- scale_y_continuous(limits = c(0, 3800), breaks = c(0, 1000, 2000, 3000),
                                  expand = c(0, 0))
no_bg <- theme(plot.background = element_rect(fill = NA, colour = NA))
tight <- theme(plot.margin = margin(1, 1, 1, 1))
## `stack`: the casualty column; `named`: axis titles, on the first and last columns.
panel <- function(layer, theta = NULL, stack = FALSE, named = FALSE) {
  p <- ggplot() + layer + x_scale + labs(x = NULL, y = NULL, fill = NULL)
  if (stack) {
    p <- p + count_scale
  } else {
    p <- p + temp_scale
  }
  if (named) {
    p <- p + labs(x = "month", y = if (stack) { "casualties" } else { "temperature" })
  }
  if (is.null(theta)) {
    p + theme_lex_viz(base_size = 7, grid = "xy", arrows = "xy") +
      theme(axis.text = element_blank()) + no_bg + tight
  } else {
    p + coord_radial(theta = theta, expand = FALSE) +
      guides(theta = if (named) { "axis_theta" } else { "none" },
             r = if (named) { "axis" } else { "none" }) +
      theme_lex_viz(base_size = 7, grid = "xy", arrows = "") +
      theme(axis.text = element_blank()) + no_bg + tight
  }
}
text <- function(label, rot = 0) {
  wrap_elements(grid::textGrob(label, rot = rot, gp = grid::gpar(
    fontfamily = "Quicksand", fontsize = 7, col = "#535353")), clip = FALSE)
}
last <- names(layers) == "stack"
named <- names(layers) %in% c("area", "stack")

## One table: the four layers in columns; Cartesian, then each polar
## transformation, in rows.
cells <- c(
  list(plot_spacer(), text("Area"), text("Points"), text("Line"), text("Stacked bars"),
       text("Cartesian", rot = 90)),
  Map(panel, layers, stack = last, named = named),
  list(text('theta = "x"', rot = 90)),
  Map(panel, layers, theta = "x", stack = last, named = named),
  list(text('theta = "y"', rot = 90)),
  Map(panel, layers, theta = "y", stack = last, named = named)
)

p <- wrap_plots(cells, ncol = 5, widths = c(0.12, 1, 1, 1, 1),
                heights = c(0.07, 0.8, 1, 1)) +
  plot_annotation(
    title = "Temperature peaks in July, road casualties in December",
    subtitle = paste(
      "Monthly means. Nottingham air temperature, 1920–1939; bars, British car",
      paste0(coloured("drivers", "driver"), ","),
      coloured("front", "front passenger"), "and",
      coloured("rear passengers", "rear passenger"),
      "killed or seriously injured, 1969–1982"
    ),
    caption = "Data: Anderson 1979; Harvey 1989, Durbin & Koopman 2001; via the R datasets package",
    theme = theme_lex_viz() + no_bg
  ) &
  no_bg &
  theme(legend.position = "none")