berryFunctions (version 1.11.0)

owa: Overwrite argument default lists

Description

combine default and user-specified argument lists. Expansion of ellipsis (three dots). Used in functions that pass argument lists separately to several functions. Internal defaults can be set per function (eg. one list for plot and one for legend). Some of the defaults can be overwritten, some should be left unchanged, some can be additionally specified by users. owa combines everything accordingly. See the example section on how to implement this.

Usage

owa(d, a, ...)

Arguments

d

Default arguments

a

Arguments specified by user

...

Names of unchangeable arguments (that will not be overwritten) as character strings (can also be a vector with characters strings).

Value

Always a list, disregarding list/vector mode of input

References

http://stackoverflow.com/questions/3057341 http://stackoverflow.com/questions/5890576 http://stackoverflow.com/questions/4124900 http://stackoverflow.com/questions/16774946

Examples

# basic usage of owa itself:
d <- list(bb=1:5, lwd="was d", lty=1,   col="gray")
a <- list(bb=3,   lwd=5, lty="from a", wachs="A")
owa(d,a) # all changed, wachs added
owa(d, a, "bb", "lwd") # lty is overwritten, bb and lwd are ignored
owa(d, NULL, "bb", "wachs") # NULL is a good default for argument lists
owa(d, c(HH=2, BBB=3) ) # vectors and lists are all converted to lists
owa(d, list(lwd=5, bb=3, lty="1") ) # order of arguments doesn't matter
owa(d, a, c("bb","lwd") ) # unchangable can also be a named vector
owa(d, a, c("bb","lwd"), c("lty","dummy") ) # or several vectors

# Usage example (see applications eg. in funnelPlot, colPoints or mReg)

# Why we want to do this:
testfun <- function(...) {plot(7:9, ...) ; legend("top", "Text hier", ...)}
testfun()
# testfun(type="o") # Error: legend doesn't have the argument 'type'!

# How to solve this:
testfun <- function(data=7:9, legarg=NULL, plotarg=NULL)
   {
   # defaults for plot and legend:
   plot_def <- list(x=0.5*data, col="red", cex=2, lty=2, type="o")
   leg_def <- list(x="top", lty=2, legend="Default text here")
   # combine defaults and user specified into final argument list
   plot_fin <- owa(d=plot_def, a=plotarg, "col", "lty")
   leg_fin <- owa(d=leg_def, a=legarg, "lty")
   # Execute single functions that each have their own arguments:
   do.call(  plot, args=plot_fin)
   do.call(legend, args=leg_fin)
   }

testfun()
testfun(plotarg=list(type="l", col="blue") )
# color is silently ignored, as it is defined as unchangeable
testfun(plotarg=list(type="l"), legarg=list(col="blue", pch=16) )