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# Create a new layer
# Layer objects store the layer of an object.
#
# They have the following attributes:
#
# * data
# * geom + parameters
# * statistic + parameters
# * position + parameters
# * aesthetic mapping
#
# Can think about grob creation as a series of data frame transformations.
Layer <- proto(expr = {
geom <- NULL
geom_params <- NULL
stat <- NULL
stat_params <- NULL
data <- NULL
mapping <- NULL
position <- NULL
params <- NULL
inherit.aes <- FALSE
new <- function (., geom=NULL, geom_params=NULL, stat=NULL, stat_params=NULL, data=NULL, mapping=NULL, position=NULL, params=NULL, ..., inherit.aes = TRUE, legend = NA, subset = NULL) {
if (is.null(geom) && is.null(stat)) stop("Need at least one of stat and geom")
data <- fortify(data)
if (!is.null(mapping) && !inherits(mapping, "uneval")) stop("Mapping should be a list of unevaluated mappings created by aes or aes_string")
if (is.character(geom)) geom <- Geom$find(geom)
if (is.character(stat)) stat <- Stat$find(stat)
if (is.character(position)) position <- Position$find(position)$new()
if (is.null(geom)) geom <- stat$default_geom()
if (is.null(stat)) stat <- geom$default_stat()
if (is.null(position)) position <- geom$default_pos()$new()
match.params <- function(possible, params) {
if ("..." %in% names(possible)) {
params
} else {
params[match(names(possible), names(params), nomatch=0)]
}
}
if (is.null(geom_params) && is.null(stat_params)) {
params <- c(params, list(...))
params <- rename_aes(params) # Rename American to British spellings etc
geom_params <- match.params(geom$parameters(), params)
stat_params <- match.params(stat$parameters(), params)
stat_params <- stat_params[setdiff(names(stat_params),
names(geom_params))]
} else {
geom_params <- rename_aes(geom_params)
}
if (!is.null(geom_params)) {
set_aesthetics <- geom_params[intersect(names(geom_params), .all_aesthetics)]
# Check that all set aesthetics have length 1
if (length(set_aesthetics) > 0) {
lengths <- sapply(set_aesthetics, length)
if (any(lengths > 1)) {
stop("When _setting_ aesthetics, they may only take one value. ",
"Problems: ",
paste(names(set_aesthetics)[lengths > 1], collapse = ","),
call. = FALSE)
}
}
}
proto(.,
geom=geom, geom_params=geom_params,
stat=stat, stat_params=stat_params,
data=data, mapping=mapping, subset=subset,
position=position,
inherit.aes = inherit.aes,
legend = legend
)
}
clone <- function(.) as.proto(.$as.list(all.names=TRUE))
use_defaults <- function(., data) {
mapped_vars <- .$mapping[!sapply(.$mapping, is.character)]
df <- aesdefaults(data, .$geom$default_aes(), mapped_vars)
# Override mappings with parameters
gp <- intersect(c(names(df), .$geom$required_aes), names(.$geom_params))
if (length(.$geom_params[gp]))
gp <- gp[sapply(.$geom_params[gp], is.atomic)]
df[gp] <- .$geom_params[gp]
df
}
pprint <- function(.) {
if (is.null(.$geom)) {
cat("Empty layer\n")
return(invisible());
}
if (!is.null(.$mapping)) {
cat("mapping:", clist(.$mapping), "\n")
}
.$geom$print(newline=FALSE)
cat(clist(.$geom_params), "\n")
.$stat$print(newline=FALSE)
cat(clist(.$stat_params), "\n")
.$position$print()
}
layer_mapping <- function(., mapping = NULL) {
# For certain geoms, it is useful to be able to ignore the default
# aesthetics and only use those set in the layer
if (.$inherit.aes) {
aesthetics <- compact(defaults(.$mapping, mapping))
} else {
aesthetics <- .$mapping
}
# Drop aesthetics that are set or calculated
set <- aesthetics %in% names(.$geom_params)
calculated <- is_calculated_aes(aesthetics)
aesthetics[!set && !calculated]
}
# Produce data.frame of evaluated aesthetics
# Depending on the construction of the layer, we may need
# to stitch together a data frame using the defaults from plot\$mapping
# and overrides for a given geom.
compute_aesthetics <- function(., data, plot) {
aesthetics <- .$layer_mapping(plot$mapping)
if (!is.null(.$subset)) {
include <- data.frame(eval.quoted(.$subset, data, emptyenv()))
data <- data[rowSums(include, na.rm = TRUE) == ncol(include), ]
}
# Override grouping if set in layer.
if (!is.null(.$geom_params$group)) {
aesthetics["group"] <- .$geom_params$group
}
plot$scales$add_defaults(data, aesthetics, plot$plot_env)
# Evaluate aesthetics in the context of their data frame
evaled <- compact(
eval.quoted(aesthetics, data, plot$plot_env))
# if (length(evaled) == 0) return(data.frame())
# evaled <- evaled[sapply(evaled, is.atomic)]
data.frame(evaled, PANEL = data$PANEL)
}
calc_statistic <- function(., data, scales) {
if (empty(data)) return(data.frame())
check_required_aesthetics(.$stat$required_aes,
c(names(data), names(.$stat_params)),
paste("stat_", .$stat$objname, sep=""))
res <- do.call(.$stat$calculate_groups, c(
list(data=as.name("data"), scales=as.name("scales")),
.$stat_params)
)
if (is.null(res)) return(data.frame())
res
}
# Map new aesthetic names
# After the statistic transformation has been applied, a second round
# of aesthetic mappings occur. This allows the mapping of variables
# created by the statistic, for example, height in a histogram, levels
# on a contour plot.
#
# This also takes care of applying any scale transformations that might
# be necessary
map_statistic <- function(., data, plot) {
if (empty(data)) return(data.frame())
aesthetics <- defaults(.$mapping,
defaults(plot$mapping, .$stat$default_aes()))
new <- strip_dots(aesthetics[is_calculated_aes(aesthetics)])
if (length(new) == 0) return(data)
# Add map stat output to aesthetics
stat_data <- as.data.frame(lapply(new, eval, data, baseenv()))
names(stat_data) <- names(new)
# Add any new scales, if needed
plot$scales$add_defaults(data, new, plot$plot_env)
# Transform the values, if the scale say it's ok
# (see stat_spoke for one exception)
if (.$stat$retransform) {
stat_data <- plot$scales$transform_df(stat_data)
}
cunion(stat_data, data)
}
reparameterise <- function(., data) {
if (empty(data)) return(data.frame())
.$geom$reparameterise(data, .$geom_params)
}
adjust_position <- function(., data, scales) {
ddply(data, "PANEL", function(data) {
.$position$adjust(data, scales)
})
}
make_grob <- function(., data, scales, cs) {
if (empty(data)) return(zeroGrob())
data <- .$use_defaults(data)
check_required_aesthetics(.$geom$required_aes, c(names(data), names(.$geom_params)), paste("geom_", .$geom$objname, sep=""))
if (is.null(data$group)) data$group <- 1
# If ordering is set, modify group variable according to this order
if (!is.null(data$order)) {
data$group <- id(list(data$group, data$order))
data$order <- NULL
}
data <- data[order(data$group), ]
do.call(.$geom$draw_groups, c(
data = list(as.name("data")),
scales = list(as.name("scales")),
coordinates = list(as.name("cs")),
.$geom_params
))
}
class <- function(.) "layer"
})
layer <- Layer$new
# Is calculated aesthetic?
# Determine if aesthetic is calculated from the statistic
#
# @keywords internal
is_calculated_aes <- function(aesthetics) {
match <- "\\.\\.([a-zA-z._]+)\\.\\."
stats <- rep(F, length(aesthetics))
grepl(match, sapply(aesthetics, deparse))
}
# Strip dots
# Strip dots from expressions that represent mappings of aesthetics to output from statistics
#
# @keywords internal
strip_dots <- function(aesthetics) {
match <- "\\.\\.([a-zA-z._]+)\\.\\."
strings <- lapply(aesthetics, deparse)
strings <- lapply(strings, gsub, pattern = match, replacement = "\\1")
lapply(strings, function(x) parse(text = x)[[1]])
}
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