candlestick chart

R code of the ggplot2 example

library(ggplot2)
library(dplyr)
library(openair)

## One candle per day from the hourly measurements: the first and last hours
## of the day make the body, the lowest and highest hours the wick.
candles <- mydata |>
  filter(!is.na(no2), date >= as.POSIXct("2003-03-01", tz = "GMT"),
         date < as.POSIXct("2003-04-01", tz = "GMT")) |>
  arrange(date) |>
  mutate(day = as.Date(date)) |>
  group_by(day) |>
  summarise(open = first(no2), close = last(no2), low = min(no2), high = max(no2)) |>
  mutate(direction = ifelse(close >= open, "Higher at day's end", "Lower at day's end"))

p <- ggplot(candles, aes(x = day)) +
  geom_linerange(aes(ymin = low, ymax = high, colour = direction), linewidth = 0.4) +
  geom_rect(aes(xmin = day - 0.35, xmax = day + 0.35, ymin = pmin(open, close),
                ymax = pmax(open, close), fill = direction)) +
  scale_colour_manual(values = unname(lex_colors[c("plum", "blue")]), name = NULL) +
  scale_fill_manual(values = unname(lex_colors[c("plum", "blue")]), name = NULL) +
  scale_x_date(date_breaks = "1 week", labels = scales::label_date("%d %b", locale = "en")) +
  scale_y_continuous(labels = lex_number, limits = c(0, NA), expand = expansion(mult = c(0, 0.05))) +
  labs(title = "Hourly nitrogen dioxide topped 100 ppb on 8 of the 31 days;\nit ended the day higher at most 4 days in a row",
       subtitle = "Daily candles: first and last hour (body), lowest and highest hour (wick)",
       x = "March 2003", y = expression(NO[2]~"(ppb)"),
       caption = "Data: London Air Quality Network, Marylebone Road, via the openair R package") +
  theme_lex_viz(grid = "y", arrows = "y") +
  theme(legend.position = "top")