# banking: Banking In lattice: Trellis Graphics for R

## Description

Calculates banking slope

## Usage

 `1` ```banking(dx, dy) ```

## Arguments

 `dx, dy` vector of consecutive x, y differences.

## Details

`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 `dx` and `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 `lattice.options("banking")`.

## Author(s)

Deepayan Sarkar Deepayan.Sarkar@R-project.org

## References

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.

`Lattice`, `xyplot`
 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15``` ```## 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") ```