#' Timeline label
#'
#' `geom_timeline_label` adds text directly to the timeline plot.
#'
#' geom_timeline_label() is for adding annotations to the earthquake data.
#' This geom adds a vertical line to each data point with a text annotation
#' (e.g. the location of the earthquake) attached to each line.
#' There should be an option to subset to n_max number of earthquakes,
#' where we take the n_max largest (by magnitude) earthquakes.
#' Aesthetics are x, which is the date of the earthquake and label which
#' takes the column name from which annotations will be obtained.
#'
#' @section Aesthetics:
#' geom_timeline understand the following aesthetics (required aesthetics are 'x' and 'label'):
#' \describe{
#' \item{x}{datetime of the event}
#' \item{label}{the text to display}
#' \item{size}{the size of the circle drawn at the event}
#' \item{colour}{the colour of the circle drawn at the event}
#' \item{y}{free groupiong parameter}
#' }
#'
#'
#' @param n_max The number of the max size events to display the label.
#' @param parse If TRUE, the labels will be parsed into expressions and
#' displayed as described in ?plotmath
#' @param check_overlap If `TRUE`, text that overlaps previous text in the
#' same layer will not be plotted.
#' @export
#' @author József Varga
#' @name geom_timeline_label
#' @examples
#' eqdta <- eq_location_clean(eq_clean_data(earthquakes)) %>%
#' filter( date > ymd("20000101") & COUNTRY=="USA") %>%
#' head(n=5)
#'
#' ggplot (data = eqdta,
#' aes(
#' x = date,
#' y = COUNTRY,
#' label = LOCATION_NAME,
#' size = FOCAL_DEPTH,
#' colour = EQ_PRIMARY
#' )) +
#' geom_timeline() +
#' geom_timeline_label(n_max=6)
geom_timeline_label <- function(mapping = NULL, data = NULL,
stat = "identity", position = "identity",
...,
n_max = 5,
parse = FALSE,
check_overlap = FALSE,
na.rm = FALSE,
show.legend = NA,
inherit.aes = TRUE)
{
layer(
data = data,
mapping = mapping,
stat = stat,
geom = GeomTimelineLabel,
position = position,
show.legend = show.legend,
inherit.aes = inherit.aes,
params = list(
parse = parse,
check_overlap = check_overlap,
na.rm = na.rm,
...,
n_max = n_max
)
)
}
#' @format NULL
#' @usage NULL
#' @export
GeomTimelineLabel <- ggplot2::ggproto("GeomTimelineLabel", ggplot2::Geom,
required_aes = c("x", "label"),
default_aes = ggplot2::aes(
colour = "black", size = 3.88, angle = 0, hjust = 0.5,
vjust = 0.5, alpha = NA, family = "", fontface = 1, lineheight = 1.2
),
draw_panel = function(data, panel_params, coord, n_max = 5,
parse = FALSE,
na.rm = FALSE, check_overlap = FALSE) {
lab <- data$label
# Filter the top 3 by each y line
data <- data %>%
group_by(y) %>%
top_n(n = n_max, wt = size)
data <- coord$transform(data, panel_params)
text_grob <-grid::textGrob(
lab,
data$x, data$y+.1, default.units = "native",
hjust = 0, vjust = 0.5,
rot = 45,
gp = grid::gpar(
col = alpha("black", data$alpha),
fontsize = 10,
fontfamily = data$family,
fontface = data$fontface,
lineheight = data$lineheight
),
check.overlap = check_overlap
)
# Add the points to a gList
g_list <- grid::gList( text_grob )
# Add the marker lines to the list
for (i in 1:length(data$x)){
g_list[[length(g_list) + 1L]] <- grid::linesGrob( data$x[i], c(data$y[i], data$y[i]+0.1) )
}
# Draw both text and line
grid::gTree(children = g_list)
},
draw_key = ggplot2::draw_key_text
)
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