R/facet_set.R

In ggfun: Miscellaneous Functions for 'ggplot2'

##' add a facet label to a ggplot or change facet label of a ggplot
##'
##' @title facet_set
##' @param label a character or a named vector to label the plot
##' @param side to label the plot at which side, either 't' (top) or 'r' (right)
##' @param angle angle of the facet label. Default is 0 for side='t' and -90 for side='r'.
##' @return a ggplot with facet label
##' @export
facet_set <- function(label, side="t", angle = NULL){
    side <-  match.arg(side, c('top', 'right'))

    structure(list(
        label = label,
        side  = side,
        angle = angle
        ),
        class = "facet_set"
    )
}


## prototype of facet_set

##' add a facet label to a ggplot
##'
##' add a facet label to a ggplot which only contains 1 panel
##' @title add_facet
##' @param plot a ggplot object
##' @param label a string to label the plot
##' @param side to label the plot at which side, either 't' (top) or 'r' (right)
##' @param angle angle of the facet label. Default is 0 for side='t' and -90 for side='r'.
##' @return a ggplot with facet label
##' @importFrom ggplot2 theme
##' @importFrom ggplot2 margin
##' @importFrom ggplot2 element_rect
##' @importFrom ggplot2 element_text
##' @importFrom ggplot2 rel
##' @importFrom ggplot2 facet_grid
##' @noRd
##' @author Guangchuang Yu
## add_facet <- function(plot, label, side = 't', angle = NULL) {
##     side <- match.arg(side, c('t', 'r'))
##     lb <- paste0("'", eval(label), "'")
##     if (side == 't') {
##         lb <- paste0('~', lb)
##     } else {
##         lb <- paste0(lb, '~.')
##         if (is.null(angle))  angle <- -90
##     }

##     plot + facet_grid(eval(parse(text=lb))) +
##         theme(strip.background = element_rect(fill='grey85', colour = NA),
##               strip.text = element_text(colour = 'grey10',
##                                         size = rel(0.8),
##                                         angle = angle,
##                                         margin = margin(4.4, 4.4, 4.4, 4.4))
##               )
## }