Calculates false colors from a numeric variable (including factors, using their numeric codes) given a color scheme and breakpoints.

`level.colors(x, at, col.regions, colors = TRUE, ...)`

x

A numeric or `factor`

variable.

at

A numeric variable of breakpoints defining intervals along
the range of `x`

.

col.regions

A specification of the colors to be assigned to
each interval defined by `at`

. This could be either a vector
of colors, or a function that produces a vector of colors when
called with a single argument giving the number of colors. See
details below.

colors

logical indicating whether colors should be computed
and returned. If `FALSE`

, only the indices representing which
interval (among those defined by `at`

) each value in `x`

falls into is returned.

…

Extra arguments, ignored.

A vector of the same length as `x`

. Depending on the
`colors`

argument, this could be either a vector of colors (in
a form usable by R), or a vector of integer indices representing
which interval the values of `x`

fall in.

If `at`

has length n, then it defines n-1 intervals. Values of
`x`

outside the range of `at`

are not assigned to an
interval, and the return value is `NA`

for such values.

Colors are chosen by assigning a color to each of the n-1 intervals.
If `col.regions`

is a palette function (such as
`topo.colors`

, or the result of calling
`colorRampPalette`

), it is called with n-1 as an argument
to obtain the colors. Otherwise, if there are exactly n-1 colors in
`col.regions`

, these get assigned to the intervals. If there are
fewer than n-1 colors, `col.regions`

gets recycled. If there are
more, a more or less equally spaced (along the length of
`col.regions`

) subset is chosen.

# NOT RUN { depth.col <- with(quakes, level.colors(depth, at = do.breaks(range(depth), 30), col.regions = terrain.colors)) xyplot(lat ~ long | equal.count(stations), quakes, strip = strip.custom(var.name = "Stations"), colours = depth.col, panel = function(x, y, colours, subscripts, ...) { panel.xyplot(x, y, pch = 21, col = "transparent", fill = colours[subscripts], ...) }) # }