xkcd figure: The Stick Figure Guide

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ToledoEM

2026-08-19

How xkcdman works

The wild anatomy of a stick figure.

xkcdman() draws a stick figure defined entirely by angles (in radians) for each body segment. The figure has 8 parts:

Parameter	Body part
`angleofneck`	neck — connects head to top of spine
`angleofspine`	spine — main torso
`anglerighthumerus`	right upper arm
`anglerightradius`	right forearm
`anglelefthumerus`	left upper arm
`angleleftradius`	left forearm
`anglerightleg`	right leg
`angleleftleg`	left leg

Two other parameters control size and proportion:

scale — diameter of the head (all other segments are proportional to it). Set it to roughly 10–15% of diff(yrange).
ratioxy — diff(xrange) / diff(yrange). Corrects for axis scaling so the figure is not stretched horizontally or vertically.

All angles follow the standard mathematical convention: 0 = right, π/2 = up, π = left, 3π/2 (or −π/2) = down.

Part 1 — Anatomy diagram

Each bone is drawn separately with its own color so you can see exactly what each parameter controls. The helper below draws a single labeled figure with colored segments.

Code

# --- geometry helper: compute bone endpoints from the same formulas as xkcdman
make_figure <- function(x, y, scale, ratioxy,
                        angleofneck, angleofspine,
                        anglerighthumerus, anglerightradius,
                        anglelefthumerus,  angleleftradius,
                        anglerightleg,     angleleftleg) {

  dh  <- scale                    # head diameter
  ls  <- dh                       # spine length
  ll  <- ls * 1.2                 # leg length
  lh  <- ls * 0.6                 # humerus length
  lr  <- ls * 0.5                 # radius length

  # key joint positions
  shoulder <- c(x, y) +
    (dh / 2) * c(cos(angleofneck) * ratioxy, sin(angleofneck))
  hip <- shoulder +
    ls * c(cos(angleofspine) * ratioxy, sin(angleofspine))
  end_rh <- shoulder +
    lh * c(cos(anglerighthumerus) * ratioxy, sin(anglerighthumerus))
  end_lh <- shoulder +
    lh * c(cos(anglelefthumerus)  * ratioxy, sin(anglelefthumerus))

  seg <- function(from, angle, dist)
    data.frame(
      x    = from[1],
      y    = from[2],
      xend = from[1] + dist * cos(angle) * ratioxy,
      yend = from[2] + dist * sin(angle)
    )

  list(
    head    = data.frame(x = x, y = y, diameter = dh),
    spine   = seg(shoulder, angleofspine,       ls),
    rarm1   = seg(shoulder, anglerighthumerus,  lh),
    rarm2   = seg(end_rh,   anglerightradius,   lr),
    larm1   = seg(shoulder, anglelefthumerus,   lh),
    larm2   = seg(end_lh,   angleleftradius,    lr),
    rleg    = seg(hip,      anglerightleg,       ll),
    lleg    = seg(hip,      angleleftleg,        ll)
  )
}

# Standard upright pose — large figure centred in the plot
xrange <- c(0, 10)
yrange <- c(0, 10)
rxy    <- diff(xrange) / diff(yrange)
sc     <- 2.5   # bigger figure fills the space

f <- make_figure(
  x = 5, y = 7.2, scale = sc, ratioxy = rxy,
  angleofneck       = -pi / 2,
  angleofspine      = -pi / 2,
  anglerighthumerus = -pi / 6,
  anglerightradius  =  pi / 6,
  anglelefthumerus  = -pi / 2 - pi / 6,
  angleleftradius   = -pi / 6,
  anglerightleg     =  3 * pi / 2 - pi / 12,
  angleleftleg      =  3 * pi / 2 + pi / 12
)

colours <- c(
  head  = "#e41a1c",
  spine = "#377eb8",
  rarm1 = "#ff7f00",
  rarm2 = "#ff7f00",
  larm1 = "#4daf4a",
  larm2 = "#4daf4a",
  rleg  = "#984ea3",
  lleg  = "#a65628"
)

set.seed(99)
p_anat <- ggplot() + coord_fixed(xlim = xrange, ylim = yrange)

# head
p_anat <- p_anat +
  geom_xkcdpath(aes(x = x, y = y, diameter = diameter),
                data = f$head, colour = colours["head"],
                linewidth = 1.4, ratioxy = rxy, mask = FALSE)

# bones
bones <- c("spine", "rarm1", "rarm2", "larm1", "larm2", "rleg", "lleg")
for (b in bones) {
  p_anat <- p_anat +
    geom_xkcdpath(aes(x = x, y = y, xend = xend, yend = yend),
                  data = f[[b]], colour = colours[b],
                  linewidth = 1.4, mask = FALSE,
                  xjitteramount = 0.02, yjitteramount = 0.02)
}

library(ggrepel)

# Label origins at bone midpoints, nudged outward from figure centre
labels_df <- data.frame(
  x = c(
    f$head$x,
    (f$spine$x  + f$spine$xend)  / 2,
    (f$rarm1$x  + f$rarm1$xend)  / 2,
    (f$rarm2$x  + f$rarm2$xend)  / 2,
    (f$larm1$x  + f$larm1$xend)  / 2,
    (f$larm2$x  + f$larm2$xend)  / 2,
    (f$rleg$x   + f$rleg$xend)   / 2,
    (f$lleg$x   + f$lleg$xend)   / 2
  ),
  y = c(
    f$head$y,
    (f$spine$y  + f$spine$yend)  / 2,
    (f$rarm1$y  + f$rarm1$yend)  / 2,
    (f$rarm2$y  + f$rarm2$yend)  / 2,
    (f$larm1$y  + f$larm1$yend)  / 2,
    (f$larm2$y  + f$larm2$yend)  / 2,
    (f$rleg$y   + f$rleg$yend)   / 2,
    (f$lleg$y   + f$lleg$yend)   / 2
  ),
  label = c("head / scale", "angleofspine",
            "anglerighthumerus", "anglerightradius",
            "anglelefthumerus",  "angleleftradius",
            "anglerightleg",     "angleleftleg"),
  col   = unname(colours[c("head","spine","rarm1","rarm2","larm1","larm2","rleg","lleg")]),
  # nudge labels away from figure: right side +x, left side -x, head up
  nx    = c( 2.0,  0.3,  2.5,  2.8, -2.5, -2.8, -2.0,  2.0),
  ny    = c( 1.2,  0,    0.4, -0.5,  0.4, -0.5, -0.5, -0.8)
)

p_anat <- p_anat +
  geom_text_repel(
    aes(x = x, y = y, label = label, colour = col),
    data               = labels_df,
    nudge_x            = labels_df$nx,
    nudge_y            = labels_df$ny,
    family             = "xkcd",
    size               = 4,
    box.padding        = unit(0.1, "lines"),
    point.padding      = unit(0.1, "lines"),
    force              = 1,
    min.segment.length = 0.3,
    segment.size       = 0.4,
    segment.colour     = "grey50",
    seed               = 42,
    show.legend        = FALSE
  ) +
  scale_colour_identity()

p_anat <- p_anat +
  annotate("text", x = 5, y = 9.3,
           label = "xkcdman anatomy", family = "xkcd", size = 6) +
  annotate("text", x = 5, y = 8.9,
           label = "angleofneck connects head to shoulder",
           family = "xkcd", size = 3, colour = "grey40") +
  theme_xkcd() +
  theme(axis.text = element_blank(), axis.ticks = element_blank(),
        axis.title = element_blank())

p_anat

Part 2 — Pose gallery

Six figures in a faceted layout, each with a different pose. Every figure uses the same helper so we only specify the angles that change.

Code

# Helper: return list(segs = df, head = df) for one pose
pose_segments <- function(pose_name, x, y, scale, ratioxy,
                          angleofneck, angleofspine,
                          anglerighthumerus, anglerightradius,
                          anglelefthumerus,  angleleftradius,
                          anglerightleg,     angleleftleg) {

  f <- make_figure(x, y, scale, ratioxy,
                   angleofneck, angleofspine,
                   anglerighthumerus, anglerightradius,
                   anglelefthumerus,  angleleftradius,
                   anglerightleg,     angleleftleg)

  segs <- do.call(rbind, lapply(
    c("spine","rarm1","rarm2","larm1","larm2","rleg","lleg"),
    function(b) { d <- f[[b]]; d$part <- b; d }
  ))
  segs$pose <- pose_name

  head_df <- data.frame(x = f$head$x, y = f$head$y,
                        diameter = f$head$diameter,
                        xend = NA_real_, yend = NA_real_,
                        part = "head", pose = pose_name)

  list(segs = segs, head = head_df)
}

# Helper: vary one angle across values, return list(segs=df, heads=df)
vary_angle <- function(param, values, labels) {
  all_segs  <- NULL
  all_heads <- NULL
  for (i in seq_along(values)) {
    args <- neutral
    args[[param]] <- values[i]
    r <- pose_segments(
      pose_name         = labels[i],
      x = 5, y = 7.2, scale = 1.4, ratioxy = 1,
      angleofneck       = args$angleofneck,
      angleofspine      = args$angleofspine,
      anglerighthumerus = args$anglerighthumerus,
      anglerightradius  = args$anglerightradius,
      anglelefthumerus  = args$anglelefthumerus,
      angleleftradius   = args$angleleftradius,
      anglerightleg     = args$anglerightleg,
      angleleftleg      = args$angleleftleg
    )
    all_segs  <- rbind(all_segs,  r$segs)
    all_heads <- rbind(all_heads, r$head)
  }
  list(segs = all_segs, heads = all_heads)
}

# Common geometry: square data space
xr  <- c(0, 10); yr <- c(0, 10); rxy <- 1; sc <- 1.4

poses <- list(
  # 1. Standing at rest
  pose_segments("Standing",
    x = 5, y = 7.2, scale = sc, ratioxy = rxy,
    angleofneck       = -pi/2,
    angleofspine      = -pi/2,
    anglerighthumerus = -pi/6,
    anglerightradius  =  pi/6,
    anglelefthumerus  = -pi/2 - pi/6,
    angleleftradius   = -pi/6,
    anglerightleg     =  3*pi/2 - pi/12,
    angleleftleg      =  3*pi/2 + pi/12),

  # 2. Arms raised (cheering)
  pose_segments("Arms up",
    x = 5, y = 7.2, scale = sc, ratioxy = rxy,
    angleofneck       = -pi/2,
    angleofspine      = -pi/2,
    anglerighthumerus =  pi/3,
    anglerightradius  =  pi/2,
    anglelefthumerus  =  pi - pi/3,
    angleleftradius   =  pi/2,
    anglerightleg     =  3*pi/2 - pi/12,
    angleleftleg      =  3*pi/2 + pi/12),

  # 3. Walking (leaning forward, legs apart)
  pose_segments("Walking",
    x = 5, y = 7.4, scale = sc, ratioxy = rxy,
    angleofneck       = -pi/2 + pi/10,
    angleofspine      = -pi/2 + pi/10,
    anglerighthumerus =  pi/2 + pi/6,
    anglerightradius  =  pi/2,
    anglelefthumerus  = -pi/6,
    angleleftradius   =  0,
    anglerightleg     =  3*pi/2 - pi/5,
    angleleftleg      =  3*pi/2 + pi/4),

  # 4. Pointing right
  pose_segments("Pointing",
    x = 5, y = 7.2, scale = sc, ratioxy = rxy,
    angleofneck       = -pi/2,
    angleofspine      = -pi/2,
    anglerighthumerus =  0,
    anglerightradius  =  0,
    anglelefthumerus  = -pi/2 - pi/6,
    angleleftradius   = -pi/6,
    anglerightleg     =  3*pi/2 - pi/12,
    angleleftleg      =  3*pi/2 + pi/12),

  # 5. Sitting (spine horizontal, legs bent)
  pose_segments("Sitting",
    x = 5, y = 5.8, scale = sc, ratioxy = rxy,
    angleofneck       = -pi/2,
    angleofspine      =  0,
    anglerighthumerus = -pi/2 - pi/6,
    anglerightradius  = -pi/2,
    anglelefthumerus  = -pi/2 + pi/6,
    angleleftradius   = -pi/2,
    anglerightleg     =  pi/2,
    angleleftleg      =  pi/2 + pi/2),

  # 6. Falling / off-balance
  pose_segments("Falling",
    x = 5, y = 7.0, scale = sc, ratioxy = rxy,
    angleofneck       = -pi/2 - pi/4,
    angleofspine      = -pi/2 - pi/4,
    anglerighthumerus =  pi/4,
    anglerightradius  =  pi/2,
    anglelefthumerus  =  pi - pi/8,
    angleleftradius   =  pi/2 + pi/4,
    anglerightleg     =  3*pi/2 + pi/6,
    angleleftleg      =  3*pi/2 - pi/3)
)

# Combine into one data frame
all_segs <- do.call(rbind, lapply(poses, `[[`, "segs"))
all_heads <- do.call(rbind, lapply(poses, `[[`, "head"))

part_colours <- c(
  head  = "#e41a1c",
  spine = "#377eb8",
  rarm1 = "#ff7f00", rarm2 = "#ff7f00",
  larm1 = "#4daf4a", larm2 = "#4daf4a",
  rleg  = "#984ea3",
  lleg  = "#a65628"
)

all_segs$colour  <- part_colours[all_segs$part]
all_heads$colour <- part_colours["head"]

# Fix facet order
pose_order <- c("Standing","Arms up","Walking","Pointing","Sitting","Falling")
all_segs$pose  <- factor(all_segs$pose,  levels = pose_order)
all_heads$pose <- factor(all_heads$pose, levels = pose_order)

set.seed(42)

p_poses <- ggplot() +
  # draw each bone segment
  geom_xkcdpath(
    aes(x = x, y = y, xend = xend, yend = yend, colour = colour),
    data = all_segs,
    linewidth = 1.3, mask = FALSE,
    xjitteramount = 0.04, yjitteramount = 0.04,
    inherit.aes = FALSE
  ) +
  # draw each head circle
  geom_xkcdpath(
    aes(x = x, y = y, diameter = diameter, colour = colour),
    data = all_heads,
    linewidth = 1.3, ratioxy = 1, mask = FALSE,
    inherit.aes = FALSE
  ) +
  scale_colour_identity(
    guide  = "legend",
    name   = "Body part",
    breaks = part_colours[c("head","spine","rarm1","larm1","rleg","lleg")],
    labels = c("head / scale","spine","right arm","left arm","right leg","left leg")
  ) +
  facet_wrap(~ pose, ncol = 3) +
  coord_fixed(xlim = xr, ylim = yr) +
  theme_xkcd() +
  theme(
    axis.text  = element_blank(),
    axis.ticks = element_blank(),
    axis.title = element_blank(),
    strip.text = element_text(family = "xkcd", size = 13)
  ) +
  labs(title = "xkcdman pose gallery")

p_poses

Part 3 — Angle reference

The figure below shows the same upright figure four times, varying one parameter at a time across a row, so you can see directly how each angle value changes the pose.

Code

# Neutral (upright) pose used as baseline
neutral <- list(
  angleofneck       = -pi/2,
  angleofspine      = -pi/2,
  anglerighthumerus = -pi/6,
  anglerightradius  =  pi/6,
  anglelefthumerus  = -pi/2 - pi/6,
  angleleftradius   = -pi/6,
  anglerightleg     =  3*pi/2 - pi/12,
  angleleftleg      =  3*pi/2 + pi/12
)

params_to_vary <- list(
  list(p = "angleofspine",
       v = c(-pi/2, -pi/2 + pi/6, -pi/2 + pi/3, 0),
       l = c("spine: -pi/2\n(upright)", "spine: -pi/3", "spine: -pi/6", "spine: 0\n(horizontal)")),
  list(p = "anglerighthumerus",
       v = c(-pi/6, 0, pi/4, pi/2),
       l = c("rarm: -pi/6\n(rest)", "rarm: 0\n(right)", "rarm: pi/4", "rarm: pi/2\n(up)")),
  list(p = "anglerightleg",
       v = c(3*pi/2 - pi/12, 3*pi/2 - pi/4, 3*pi/2 + pi/4, 3*pi/2 - pi/2),
       l = c("rleg: rest", "rleg: back", "rleg: forward", "rleg: up")),
  list(p = "anglelefthumerus",
       v = c(-pi/2-pi/6, pi-pi/6, pi/2+pi/6, pi),
       l = c("larm: rest", "larm: left", "larm: up-left", "larm: out"))
)

ref_segs  <- do.call(rbind, lapply(params_to_vary, function(pv) {
  r <- vary_angle(pv$p, pv$v, pv$l)
  r$segs$group_param <- pv$p
  r$segs
}))

ref_heads <- do.call(rbind, lapply(params_to_vary, function(pv) {
  r <- vary_angle(pv$p, pv$v, pv$l)
  r$heads$group_param <- pv$p
  r$heads
}))

ref_segs$colour  <- part_colours[ref_segs$part]
ref_heads$colour <- part_colours["head"]

# highlighted part per param group
highlight_map <- c(
  angleofspine      = "#377eb8",
  anglerighthumerus = "#ff7f00",
  anglerightleg     = "#984ea3",
  anglelefthumerus  = "#4daf4a"
)

ref_segs$colour <- ifelse(
  (ref_segs$part == "spine"  & ref_segs$group_param == "angleofspine") |
  (ref_segs$part == "rarm1"  & ref_segs$group_param == "anglerighthumerus") |
  (ref_segs$part == "rarm2"  & ref_segs$group_param == "anglerighthumerus") |
  (ref_segs$part == "rleg"   & ref_segs$group_param == "anglerightleg") |
  (ref_segs$part == "larm1"  & ref_segs$group_param == "anglelefthumerus") |
  (ref_segs$part == "larm2"  & ref_segs$group_param == "anglelefthumerus"),
  ref_segs$colour,
  "grey70"
)

# Facet label: combine group_param + pose
ref_segs$facet_label  <- paste0(ref_segs$group_param,  "\n", ref_segs$pose)
ref_heads$facet_label <- paste0(ref_heads$group_param, "\n", ref_heads$pose)

# Build ordered factor across all 16 facets
facet_order <- unlist(lapply(params_to_vary, function(pv)
  paste0(pv$p, "\n", pv$l)
))
ref_segs$facet_label  <- factor(ref_segs$facet_label,  levels = facet_order)
ref_heads$facet_label <- factor(ref_heads$facet_label, levels = facet_order)

set.seed(7)

p_ref <- ggplot() +
  geom_xkcdpath(
    aes(x = x, y = y, xend = xend, yend = yend, colour = colour),
    data = ref_segs,
    linewidth = 1.2, mask = FALSE,
    xjitteramount = 0.03, yjitteramount = 0.03,
    inherit.aes = FALSE
  ) +
  geom_xkcdpath(
    aes(x = x, y = y, diameter = diameter),
    data = ref_heads,
    linewidth = 1.2, colour = "#e41a1c", ratioxy = 1, mask = FALSE,
    inherit.aes = FALSE
  ) +
  scale_colour_identity() +
  facet_wrap(~ facet_label, ncol = 4) +
  coord_fixed(xlim = xr, ylim = yr) +
  theme_xkcd() +
  theme(
    axis.text  = element_blank(),
    axis.ticks = element_blank(),
    axis.title = element_blank(),
    strip.text = element_text(family = "xkcd", size = 9)
  ) +
  labs(title = "Angle reference: one parameter varied per row")

p_ref

Quick reference card

angleofspine      -pi/2  upright  |  0  horizontal  |  pi/2  upside down
angleofneck       match angleofspine for natural look
anglerighthumerus -pi/6  hanging  |  0  right  |  pi/2  raised
anglerightradius  follow anglerighthumerus + pi/6 for natural elbow bend
anglelefthumerus  mirror of right: -pi/2 - anglerighthumerus
angleleftradius   mirror of right
anglerightleg     3*pi/2 - pi/12   (slight outward spread)
angleleftleg      3*pi/2 + pi/12   (slight outward spread)

scale     ~10-15% of diff(yrange)
ratioxy   diff(xrange) / diff(yrange)   -- always set this!

These binaries (installable software) and packages are in development.
They may not be fully stable and should be used with caution. We make no claims about them.
Health stats visible at Monitor.