Time-indexed colour.

Create a time-indexed colour map, useful for maintaining an absolute scale across time series as a function of date-time.

mk_timePal(x, col)

Arguments

x

date-times

col

colours, can be a function or an actual set of colours

Value

function of date-time

Examples

dts <- seq(as.Date("1749-01-01"), by = "1 month", length.out = length(sunspots))
d <- data.frame(date = dts, sunspots = as.vector(t(sunspots)))
tpal <- mk_timePal(d$date, col = sst_pal(50))
par(mfrow  = c(2, 1))
plot(sunspots ~ date, col = tpal(date), data = d)
## colours maintained by absolute date
plot(sunspots ~ date, col = tpal(date), data = d[1500:1800, ], cex = 2)
## we can now insert new points and maintain this colour ramp
d2 <- data.frame(date = seq(min(d$date), max(d$date), by = "5 days"))
d2$sunspots <- approxfun(d$date, d$sunspots)(d2$date)
points(sunspots ~ date, col = tpal(date), data = d2, pch = 19, cex = 0.5)