Geometry of the faded "ghost" vintages behind a drawn technology

Collects the ghost-stack settings of draw() into one object, so the drawing methods keep a short signature. Pass either this constructor or a plain named list: draw(x, ghost = list(drift = 0.2)) is merged onto the defaults. Unknown names are an error in both forms – misspelling a flat argument used to be swallowed silently by ... and forwarded downstream.

Usage

ghost_options(
  alpha = 0.45,
  alpha_min = 0.12,
  scale = 0.72,
  drift = 0.17,
  rise = 0,
  stamp = TRUE
)

Arguments

alpha

opacity of the nearest ghost; further ones fade towards alpha_min.

alpha_min

opacity of the furthest ghost.

scale, drift, rise

geometry of the ghost stack, all describing the FURTHEST ghost rather than a per-step increment: its size relative to the selected figure, and how far it is offset horizontally and vertically (in npc). Intermediate ghosts interpolate. Defining the total extent this way keeps a technology with thirty annual vintages inside the viewport – a per-step offset would put it off-canvas. rise defaults to 0: with ghost arrows suppressed there is nothing for a vertical offset to clear, so the stack reads better as a flat fan.

stamp

label each ghost with its vintage. The first, last and selected vintages are always stamped; intermediate ones only when the spacing leaves room, so a dense stack does not turn into overlapping text.

Value

a list of class ghost_options.

See also

Other draw: plot(), theme_energyRt()

Examples

ghost_options(drift = 0.25, stamp = FALSE)
#> $alpha
#> [1] 0.45
#> 
#> $alpha_min
#> [1] 0.12
#> 
#> $scale
#> [1] 0.72
#> 
#> $drift
#> [1] 0.25
#> 
#> $rise
#> [1] 0
#> 
#> $stamp
#> [1] FALSE
#> 
#> attr(,"class")
#> [1] "ghost_options"