# banking

##### Banking

Calculates banking slope

- Keywords
- dplot

##### Usage

`banking(dx, dy)`

##### 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")`

.

##### References

Cleveland, William S., McGill, Marylyn E. and McGill, Robert (1988),
"The Shape Parameter of a Two-variable Graph",
*Journal of the American Statistical Association*, 83, 289-300

##### See Also

##### Examples

```
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 0.17-10, License: GPL (>= 2)*