Color coding legend for factors

Source: R/trellis_factor_key.R

Modifies a list of lattice arguments (as for lattice::levelplot(), etc.) according to the factor levels. The colorkey will shows all levels (including unused), and the drawing colors will be set accordingly.

trellis.factor.key(f, levelplot.args = list())

Arguments

f

the factor that will be color-coded

levelplot.args

a list with levelplot arguments

Value

the modified list with levelplot arguments.

Details

trellis.factor.key is used during levelplot-based plotting of factors (for hyperSpec objects) unless transform.factor = FALSE is specified.

Author

C. Beleites

Examples


faux_cell$z <- factor(rep(c("a", "a", "d", "c"),
  length.out = nrow(faux_cell)
),
levels = letters[1:4]
)

str(trellis.factor.key(faux_cell$z))
#> List of 3
#>  $ at         : num [1:5] 0.5 1.5 2.5 3.5 4.5
#>  $ col.regions: chr [1:4] "#FCFFDD" "#98DCBB" "#0095AF" "#26185F"
#>  $ colorkey   :List of 1
#>   ..$ lab:List of 2
#>   .. ..$ at : int [1:4] 1 2 3 4
#>   .. ..$ lab: chr [1:4] "a" "b" "c" "d"

plot_map(faux_cell, z ~ x * y)
#> Warning: device support for raster images unknown, ignoring 'raster=TRUE'


## switch off using trellis.factor.key:
## note that the factor levels are collapsed to c(1, 2, 3) rather than
## c (1, 3, 4)
plot_map(faux_cell, z ~ x * y, transform.factor = FALSE)
#> Warning: device support for raster images unknown, ignoring 'raster=TRUE'


plot_map(faux_cell, z ~ x * y,
  col.regions = c("gray", "red", "blue", "dark green")
)
#> Warning: device support for raster images unknown, ignoring 'raster=TRUE'