synopsis
parallel(formula, data = parent.frame(), aspect = "fill", between = list(x = 0.5,
y = 0.5), layout = NULL, panel = panel.parallel, prepanel = NULL,
scales = list(), strip = TRUE, groups = NULL, xlab = NULL,
xlim, ylab = NULL, ylim, varnames, ..., subscripts = !is.null(groups),
subset = TRUE)