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Draw a Pie Glyph

Source: R/pieglyphGrob.R
pieglyphGrob.Rd

Uses Grid graphics to draw a circular pie or clock glyph (Ward and Lipchak 2000; Fuchs et al. 2013) .

Usage

pieglyphGrob(
  x = 0.5,
  y = 0.5,
  z,
  size = 1,
  edges = 200,
  col = "black",
  fill = NA,
  lwd = 1,
  alpha = 1,
  angle.start = 0,
  angle.stop = 2 * base::pi,
  linejoin = c("mitre", "round", "bevel"),
  scale.segment = FALSE,
  scale.radius = TRUE,
  grid.levels = NULL,
  draw.grid = FALSE,
  col.grid = "grey",
  lwd.grid = lwd
)

Arguments

x

A numeric vector or unit object specifying x-locations.

y

A numeric vector or unit object specifying y-locations.

z

A numeric vector specifying the values to be plotted as dimensions of the pie glyph according to the arguments scale.segment or scale.radius.

size

The size of glyphs (radius).

edges

The number of edges of the polygon to depict the circular glyph outline.

col

The line colour.

fill

The fill colour.

lwd

The line width.

alpha

The alpha transparency value.

angle.start

The start angle for the glyph in radians. Default is zero.

angle.stop

The stop angle for the glyph in radians. Default is \(2\pi\).

linejoin

The line join style for the pie segment polygons. Either "mitre", "round" or "bevel".

scale.segment

logical. If TRUE, the segments (pie slices) are scaled according to value of z.

scale.radius

logical. If TRUE, the radius of segments (pie slices) are scaled according to value of z.

grid.levels

A list of grid levels (as vectors) corresponding to the values in z at which grid lines are to be plotted. The values in z should be present in the list specified.

draw.grid

logical. If TRUE, grid lines are plotted along the segments when scale.radius = TRUE. Default is FALSE.

col.grid

The colour of the grid lines.

lwd.grid

The line width of the grid lines.

Value

A gTree object.

References

Fuchs J, Fischer F, Mansmann F, Bertini E, Isenberg P (2013). “Evaluation of alternative glyph designs for time series data in a small multiple setting.” In Proceedings of the SIGCHI Conference on Human Factors in Computing Systems, 3237–3246. ISBN 978-1-4503-1899-0.

Ward MO, Lipchak BN (2000). “A visualization tool for exploratory analysis of cyclic multivariate data.” Metrika, 51(1), 27–37.

See also

geom_pieglyph

Other grobs: dotglyphGrob(), metroglyphGrob(), profileglyphGrob(), starglyphGrob(), tileglyphGrob()

Examples

library(ggmultiglyph)
library(grid)
library(gridExtra)

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Adjust radius and segment scaling
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

pg1 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                   z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33),
                   size = 15)

pg2 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                   z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33),
                   size = 15, scale.radius = FALSE)

pg3 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                   z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33),
                   size = 15, scale.segment = TRUE, scale.radius = FALSE)

pg4 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33),
                    size = 15,
                    angle.start = 0, angle.stop = base::pi)

pg5 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                   z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33),
                   size = 15, scale.radius = FALSE,
                   angle.start = 0, angle.stop = base::pi)

pg6 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                   z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33),
                   size = 15, scale.segment = TRUE, scale.radius = FALSE,
                   angle.start = 0, angle.stop = base::pi)

grid.arrange(pg1, pg2, pg3, pg4, pg5, pg6, nrow = 2, ncol = 3)


#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Adjust size
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

pg1 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                     z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 5)

pg2 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                     z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 10)

pg3 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                     z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 15)

pg4 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                     z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 5,
                     angle.start = 0, angle.stop = base::pi)

pg5 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                     z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 10,
                     angle.start = 0, angle.stop = base::pi)

pg6 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                     z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 15,
                     angle.start = 0, angle.stop = base::pi)

grid.arrange(pg1, pg2, pg3, pg4, pg5, pg6, nrow = 2, ncol = 3)


pg1 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 5,
                    scale.radius = FALSE)

pg2 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 10,
                    scale.radius = FALSE)

pg3 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 15,
                    scale.radius = FALSE)

pg4 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 5,
                    scale.radius = FALSE,
                    angle.start = 0, angle.stop = base::pi)

pg5 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 10,
                    scale.radius = FALSE,
                    angle.start = 0, angle.stop = base::pi)

pg6 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 15,
                    scale.radius = FALSE,
                    angle.start = 0, angle.stop = base::pi)

grid.arrange(pg1, pg2, pg3, pg4, pg5, pg6, nrow = 2, ncol = 3)


pg1 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 5,
                    scale.segment = TRUE, scale.radius = FALSE)

pg2 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 10,
                    scale.segment = TRUE, scale.radius = FALSE)

pg3 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 15,
                    scale.segment = TRUE, scale.radius = FALSE)

pg4 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 5,
                    scale.segment = TRUE, scale.radius = FALSE,
                    angle.start = 0, angle.stop = base::pi)

pg5 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 10,
                    scale.segment = TRUE, scale.radius = FALSE,
                    angle.start = 0, angle.stop = base::pi)

pg6 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 15,
                    scale.segment = TRUE, scale.radius = FALSE,
                    angle.start = 0, angle.stop = base::pi)

grid.arrange(pg1, pg2, pg3, pg4, pg5, pg6, nrow = 2, ncol = 3)


#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Adjust line width
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

pg1 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 15)

pg2 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33),
                    size = 15, lwd = 3)

pg3 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33),
                    size = 15, lwd = 5)

pg4 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 15,
                    angle.start = 0, angle.stop = base::pi)

pg5 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33),
                    size = 15, lwd = 3,
                    angle.start = 0, angle.stop = base::pi)

pg6 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33),
                    size = 15, lwd = 5,
                    angle.start = 0, angle.stop = base::pi)

grid.arrange(pg1, pg2, pg3, pg4, pg5, pg6, nrow = 2, ncol = 3)


pg1 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 15,
                    scale.radius = FALSE)

pg2 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33),
                    size = 15, lwd = 3,
                    scale.radius = FALSE)

pg3 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33),
                    size = 15, lwd = 5,
                    scale.radius = FALSE)

pg4 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 15,
                    scale.radius = FALSE,
                    angle.start = 0, angle.stop = base::pi)

pg5 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33),
                    size = 15, lwd = 3,
                    scale.radius = FALSE,
                    angle.start = 0, angle.stop = base::pi)

pg6 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33),
                    size = 15, lwd = 5,
                    scale.radius = FALSE,
                    angle.start = 0, angle.stop = base::pi)

grid.arrange(pg1, pg2, pg3, pg4, pg5, pg6, nrow = 2, ncol = 3)


pg1 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 15,
                    scale.segment = TRUE, scale.radius = FALSE)

pg2 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33),
                    size = 15, lwd = 3,
                    scale.segment = TRUE, scale.radius = FALSE)

pg3 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33),
                    size = 15, lwd = 5,
                    scale.segment = TRUE, scale.radius = FALSE)

pg4 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 15,
                    scale.segment = TRUE, scale.radius = FALSE,
                    angle.start = 0, angle.stop = base::pi)

pg5 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33),
                    size = 15, lwd = 3,
                    scale.segment = TRUE, scale.radius = FALSE,
                    angle.start = 0, angle.stop = base::pi)

pg6 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33),
                    size = 15, lwd = 5,
                    scale.segment = TRUE, scale.radius = FALSE,
                    angle.start = 0, angle.stop = base::pi)

grid.arrange(pg1, pg2, pg3, pg4, pg5, pg6, nrow = 2, ncol = 3)


#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Adjust angle
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

pg1 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 10)

pg2 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 10,
                    angle.start = 0, angle.stop = base::pi)

pg3 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 10,
                    angle.start = 90 * (base::pi/180),
                    angle.stop = 270 * (base::pi/180))

pg4 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 10,
                    scale.radius = FALSE)

pg5 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 10,
                    scale.radius = FALSE,
                    angle.start = 0, angle.stop = base::pi)

pg6 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 10,
                    scale.radius = FALSE,
                    angle.start = 90 * (base::pi/180),
                    angle.stop = 270 * (base::pi/180))

pg7 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 10,
                    scale.segment = TRUE, scale.radius = FALSE)

pg8 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 10,
                    scale.segment = TRUE, scale.radius = FALSE,
                    angle.start = 0, angle.stop = base::pi)

pg9 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 10,
                    scale.segment = TRUE, scale.radius = FALSE,
                    angle.start = 90 * (base::pi/180),
                    angle.stop = 270 * (base::pi/180))

grid.arrange(pg1, pg2, pg3, pg4, pg5, pg6, pg7, pg8, pg9,
             nrow = 3, ncol = 3)


#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Adjust fill colour
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


pg1 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 10,
                    fill = RColorBrewer::brewer.pal(6, "Dark2"))

pg2 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 10,
                    angle.start = 0, angle.stop = base::pi,
                    fill = RColorBrewer::brewer.pal(6, "Dark2"))

pg3 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 10,
                    angle.start = 90 * (base::pi/180),
                    angle.stop = 270 * (base::pi/180),
                    fill = RColorBrewer::brewer.pal(6, "Dark2"))

pg4 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 10,
                    scale.radius = FALSE,
                    fill = RColorBrewer::brewer.pal(6, "Dark2"))

pg5 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 10,
                    scale.radius = FALSE,
                    angle.start = 0, angle.stop = base::pi,
                    fill = RColorBrewer::brewer.pal(6, "Dark2"))

pg6 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 10,
                    scale.radius = FALSE,
                    angle.start = 90 * (base::pi/180),
                    angle.stop = 270 * (base::pi/180),
                    fill = RColorBrewer::brewer.pal(6, "Dark2"))

pg7 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 10,
                    scale.segment = TRUE, scale.radius = FALSE,
                    fill = RColorBrewer::brewer.pal(6, "Dark2"))

pg8 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 10,
                    scale.segment = TRUE, scale.radius = FALSE,
                    angle.start = 0, angle.stop = base::pi,
                    fill = RColorBrewer::brewer.pal(6, "Dark2"))

pg9 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33), size = 10,
                    scale.segment = TRUE, scale.radius = FALSE,
                    angle.start = 90 * (base::pi/180),
                    angle.stop = 270 * (base::pi/180),
                    fill = RColorBrewer::brewer.pal(6, "Dark2"))

grid.arrange(pg1, pg2, pg3, pg4, pg5, pg6, pg7, pg8, pg9,
             nrow = 3, ncol = 3)


#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Adjust line join style
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

pg1 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33),
                    size = 15, lwd = 5)

pg2 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33),
                    size = 15, lwd = 5, linejoin = "round")

pg3 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(0.24, 0.3, 0.8, 1.4, 0.6, 0.33),
                    size = 15, lwd = 5, linejoin = "bevel")

grid.arrange(pg1, pg2, pg3, nrow = 1, ncol = 3)


#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Adjust grid levels
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

# Grid levels
gl <- split(x = c(rep(c(1, 2, 3), 4),
                  rep(c(1, 2, 3, 4), 2)),
            f = c(rep(1:4, each = 3),
                  rep(5:6, each = 4)))
gl
#> $`1`
#> [1] 1 2 3
#> 
#> $`2`
#> [1] 1 2 3
#> 
#> $`3`
#> [1] 1 2 3
#> 
#> $`4`
#> [1] 1 2 3
#> 
#> $`5`
#> [1] 1 2 3 4
#> 
#> $`6`
#> [1] 1 2 3 4
#> 

pg1 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(1, 3, 2, 1, 2, 3), size = 5,
                    draw.grid = TRUE, grid.levels = gl,
                    lwd = 2, col.grid = "black")

pg2 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    angle.start = 0, angle.stop = base::pi,
                    z = c(1, 3, 2, 1, 2, 3), size = 5,
                    draw.grid = TRUE, grid.levels = gl,
                    lwd = 2, col.grid = "black")

pg3 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(1, 3, 2, 1, 2, 3), size = 5,
                    scale.segment = TRUE,
                    draw.grid = TRUE, grid.levels = gl,
                    lwd = 2, col.grid = "black")

pg4 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    angle.start = 0, angle.stop = base::pi,
                    z = c(1, 3, 2, 1, 2, 3), size = 5,
                    scale.segment = TRUE,
                    draw.grid = TRUE, grid.levels = gl,
                    lwd = 2, col.grid = "black")

grid.arrange(pg1, pg2, pg3, pg4, nrow = 2, ncol = 2)


#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Adjust grid level colours
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

# Grid levels
gl <- split(x = c(rep(c(1, 2, 3), 4),
                  rep(c(1, 2, 3, 4), 2)),
            f = c(rep(1:4, each = 3),
                  rep(5:6, each = 4)))
gl
#> $`1`
#> [1] 1 2 3
#> 
#> $`2`
#> [1] 1 2 3
#> 
#> $`3`
#> [1] 1 2 3
#> 
#> $`4`
#> [1] 1 2 3
#> 
#> $`5`
#> [1] 1 2 3 4
#> 
#> $`6`
#> [1] 1 2 3 4
#> 

pg1 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(1, 3, 2, 1, 2, 3), size = 5,
                    draw.grid = TRUE, grid.levels = gl,
                    lwd = 2, col = "white", col.grid = "white",
                    fill = RColorBrewer::brewer.pal(6, "Dark2"))

pg2 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    angle.start = 0, angle.stop = base::pi,
                    z = c(1, 3, 2, 1, 2, 3), size = 5,
                    draw.grid = TRUE, grid.levels = gl,
                    lwd = 2, col = "white", col.grid = "white",
                    fill = RColorBrewer::brewer.pal(6, "Dark2"))

pg3 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    z = c(1, 3, 2, 1, 2, 3), size = 5,
                    scale.segment = TRUE,
                    draw.grid = TRUE, grid.levels = gl,
                    lwd = 2, col = "white", col.grid = "white",
                    fill = RColorBrewer::brewer.pal(6, "Dark2"))

pg4 <- pieglyphGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                    angle.start = 0, angle.stop = base::pi,
                    z = c(1, 3, 2, 1, 2, 3), size = 5,
                    scale.segment = TRUE,
                    draw.grid = TRUE, grid.levels = gl,
                    lwd = 2, col = "white", col.grid = "white",
                    fill = RColorBrewer::brewer.pal(6, "Dark2"))

grid.arrange(pg1, pg2, pg3, pg4, nrow = 2, ncol = 2)