A type of graph that combines a timeline chart and a bar chart

Question

I'm trying to plot a collection of items where each item has an x-range, and a y-value. The below variation of a bar chart is what I had in mind, but I can't find a software tool that appears designed to plot it.

E.g., perhaps comparing the customer satisfaction for four construction projects that took place in a 10-week period. (Example edited for clarity)

The goal is to be able to visualize the heights of these different items, while also taking into account their possibly-overlapping ranges. A kind of combination of a timeline chart and a bar chart.

You could hack an area chart to mostly accomplish the design below, but is there a type of graph actually designed for this kind of data?

Ex:

Answer 1

Why plot a rectangle when only its height carries information? I would plot a line segment instead.

Following a great suggestion by @whuber, I've added transparent bars below the x-axis at 0 to highlight how projects overlap in time. And I removed the legend, opting instead to show the "name" of the project to the left of its segment.

Here is the R code; I use ggplot2.

library("lubridate")
library("tidyverse")

data <-
  tribble(
    ~start_time, ~end_time, ~satisfaction, ~project,
    "2022-01-01", "2022-01-31", 9, "A",
    "2022-01-25", "2022-02-15", 8, "B",
    "2022-03-10", "2022-04-08", 5, "C",
    "2022-03-20", "2022-04-10", 6, "D"
  ) %>%
  mutate(
    across(ends_with("time"), as_date)
  )

data %>%
  ggplot() +
  geom_segment(
    aes(
      x = start_time,
      y = satisfaction,
      xend = end_time,
      yend = satisfaction,
      color = project
    ),
    size = 2
  ) +
  geom_rect(
    aes(
      xmin = start_time,
      ymin = 0,
      xmax = end_time,
      ymax = -1,
      fill = project
    ),
    alpha = 0.5
  ) +
  geom_text(
    aes(
      x = start_time,
      y = satisfaction,
      label = project,
      color = project
    ),
    inherit.aes = FALSE,
    nudge_x = -2,
    fontface = "bold",
    size = 5
  ) +

  scale_x_date() +
  scale_y_continuous(
    breaks = c(0, 2, 4, 6, 8, 10),
    limits = c(-1, 10),
    expand = c(0, 0)
  ) +

  # Draw bars in the margin as explained by @Axeman on StackOverflow:
  # https://stackoverflow.com/a/73468680/9566484)
  coord_cartesian(
    ylim = c(0, 10),
    clip = "off",
    expand = FALSE
  ) +
  theme_minimal() +
  theme(
    axis.title.x = element_blank(),
    axis.ticks.x = element_line(),
    panel.grid.minor = element_blank(),
    panel.grid.major.x = element_blank(),
    legend.position = "none"
  )

^{Created on 2022-08-24 with reprex v2.0.2}

Answer 2

A similar option for non-overlapping data ranges, especially where the bar area has meaning, could be a Marimekko/Mosaic plot.