On Tue, 29 Mar 2005, Berwin A Turlach wrote:
Dear all,
I would like to suggest changing the pairs.formula command such that a command like
pairs(GNP ~ . - Year - GNP.deflator, longley)
would behave in a similar fashion as
lm(GNP ~ . - Year - GNP.deflator, longley)
i.e., make a pairwise scatterplot of GNP and all other variables in the (longley) dataframe except for Year and GNP.deflator. The above command, with the current version of pairs.formula, produces a pairwise scatterplot of all variables in the (longley) dataframe.
After some tinkering around, I came up with the following replacement function of pairs.formula which seems to do the job:
pairs.formula <- function (formula, data = NULL, ..., subset, na.action = stats::na.pass) { m <- match.call(expand.dots = FALSE) if (is.matrix(eval(m$data, parent.frame()))) m$data <- as.data.frame(data) m$... <- NULL m$na.action <- stats::na.pass m[[1]] <- as.name("model.frame") mf <- eval(m, parent.frame())
mt <- attr(mf, "terms") tmp <- attr(mt, "factors") ind <- apply(tmp, 1, max) sv <- rownames(tmp)[ind>0] ind <- match(sv, sapply(attr(mt, "variables"), deparse, width.cutoff=500)[-1]) if( (tt <- attr(mt, "response")) != 0 ){ ind <- c(tt, ind) }
pairs(mf[,ind], ...) }
Would you please kindly consider replacing the current pairs.formula function (at the top of the file src/library/graphics/R/pairs.R) with the above function?
Perhaps you could explain what precisely 'the job' is and why you chose such an unusual piece of code to do it? (E.g. what is the prescription for the ordering of terms, and why do you think the rownames of the factors and the variables might be in different orders? They are set the same in the C code.)
BTW, the help page specifically warns against a formula of the type you specified. Why do you want to allow a response? Currently only '+' is documented to work.
-- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595
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