Calculates banking slope
- dx, dy
- vector of consecutive x, y differences.
banking is the banking function used when
aspect = "xy" in high level Trellis functions. It is usually not very meaningful except with
xyplot. It considers the absolute slopes (based on
dy) and returns a value which when adjusted by the panel scale limits will make the median of the above absolute slopes correspond to a 45 degree line.
This function was inspired by the discussion of banking in the documentation for Trellis Graphics available at Bell Labs' website (see
Lattice), but is most likely identical to an algorithm described by Cleveland et al (see below). It is not clear (to the author) whether this is the algorithm used in S-PLUS. Alternative banking rules, implemented as a similar function, can be used as a drop-in replacement by suitably modifying
Cleveland, William S. and McGill, Marylyn E. and McGill, Robert (1988) “The Shape Parameter of a Two-variable Graph”, Journal of the American Statistical Association, 83, 289--300.
## with and without banking plot <- xyplot(sunspot.year ~ 1700:1988, xlab = "", type = "l", scales = list(x = list(alternating = 2)), main = "Yearly Sunspots") print(plot, position = c(0, .3, 1, .9), more = TRUE) print(update(plot, aspect = "xy", main = "", xlab = "Year"), position = c(0, 0, 1, .3)) ## cut-and-stack plot (see also xyplot.ts) xyplot(sunspot.year ~ time(sunspot.year) | equal.count(time(sunspot.year)), xlab = "", type = "l", aspect = "xy", strip = FALSE, scales = list(x = list(alternating = 2, relation = "sliced")), as.table = TRUE, main = "Yearly Sunspots")
Documentation reproduced from package lattice, version 0.20-33. License: GPL (>= 2)