On 10/05/2012 1:53 PM, Duncan Temple Lang wrote:
Or slightly more conveniently, use the default value of getOption() to return
the vector
of color names if the option is not set, e.g.
foo<- function(x, heplot.colors = getOption("heplot.colors",
c("red", "blue", "black", "darkgreen",
"brown", "darkgray")), ...) {
If each option is only used in a small number of places, that's the
easiest solution. If they are used more widely, you have the problem of
keeping the defaults consistent. Several packages do their own
home-brewed solutions to this. In rgl it's done by having a package
global variable r3dDefaults. If a user changes it, they get their own
copy in the global environment. This means functions within rgl
need to use
get("r3dDefaults", envir=.GlobalEnv)
to do the lookups in the right place.
The igraph package also handles defaults for graph colors; I haven't
really looked into how they did it.
You can do it using lexical scoping: something like
myOptions <- local({
opt1 <- default1
opt2 <- default2
function(...) {
# If ... has no names, it's asking for values; if it has names,
then change
# the parents. Or just create two functions, one for setting,
one for getting.
}
)
Duncan Murdoch
D.
On 5/10/12 10:09 AM, Simon Urbanek wrote:
>
> On May 10, 2012, at 9:59 AM, Michael Friendly wrote:
>
>> This may be elementary, but I can't find an answer: How can I set up global
options for
>> some specific arguments to functions in a package which can be easily
changed by the user?
>>
>> This question relates to the selection of colors used in functions in
several packages (heplots,
>> genridge), where I want to provide reasonable default values for plots, but
allow users to
>> change those defaults globally for all plots produced with my functions.
>>
>> One solution is to use palette() for the default, as in
>>
>> foo<- function(x, col=palette(), ...) {}
>> but the standard palette is not appropriate for my use, and I'd rather not
hijack more typical uses
>>
>> Another is to use an explicit list of colors for default, as in
>>
>> bar<- function(x, col=c('red', 'blue', 'brown', 'darkgreen', ...), ...) {}
>> but this must be overridden each time by someone to wants to change the
defaults.
>>
>> options() seems like the way to go, but I'm not sure how to implement this.
If I use
>> a .onLoad function to set some options, will these be created in the global
environment?
>> If not, how to make them so?
>>
>> .onLoad<- function() {
>> options(heplot.colors =
>> c("red", "blue", "black", "darkgreen", "darkcyan","magenta",
"brown","darkgray"))
>
> You certainly don't want to do that - it would override user's setting and
thus defeat the whole purpose of options.
>
>
>> }
>>
>> My function could then use
>>
>> foo<- function(x, getOption("heplot.colors"), ...) {}
>>
>
> You can always do that:
>
> foo<- function(x, heplot.colors = getOption("heplot.colors"), ...) {
> if (is.null(heplot.colors)) heplot.colors<- c("red", "blue", "black", "darkgreen",
"darkcyan","magenta", "brown","darkgray")
>
> Cheers,
> Simon
>
>
>>
>> --
>> Michael Friendly Email: friendly AT yorku DOT ca
>> Professor, Psychology Dept.
>> York University Voice: 416 736-5115 x66249 Fax: 416 736-5814
>> 4700 Keele Street Web: http://www.datavis.ca
>> Toronto, ONT M3J 1P3 CANADA
>>
>> ______________________________________________
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>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>
>>
>
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