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Add tag label for adding identifier to plot (#2405)
* Add tag label for adding identifier to plot * Add plot.tag.position and modify default themes accordingly * Fix interplay between margin and justification * Set default tag size to rel(1.2) * Add brief description of use * Better error message * Fix wording in documentation * Add a few visual tests * Use justify_grobs for tag justification * Add generated visual test figures * Don't assign into unit vectors to avoid weird grid bug in R 3.2 (and possibly older) * Add comment describing the reason for the slightly weird reassembly of widths and heights * Fix visual tests for AppVeyor
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‎NEWS.md‎

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* Added `stat_qq_line()` to make it easy to add a simple line to a Q-Q plot. This
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line makes it easier to judge the fit of the theoretical distribution
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(@nicksolomon).
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* Added `tag` label for adding identification tags to the plot. A tag is added
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with the `labs()` function and styling is handled through the `plot.tag` theme
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element. Position is specified with the `plot.tag.position` theme setting and
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defauls to `"topleft"`. Tags are useful for identifying subplots in a
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multiplot figure and often used in the scientific literature (@thomasp85).
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### Scales
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‎R/plot-build.r‎

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@@ -242,6 +242,11 @@ ggplot_gtable.ggplot_built <- function(data) {
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subtitle <- element_render(theme, "plot.subtitle", plot$labels$subtitle, margin_y = TRUE)
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subtitle_height <- grobHeight(subtitle)
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# Tag
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tag <- element_render(theme, "plot.tag", plot$labels$tag, margin_y = TRUE, margin_x = TRUE)
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tag_height <- grobHeight(tag)
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tag_width <- grobWidth(tag)
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# whole plot annotation
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caption <- element_render(theme, "plot.caption", plot$labels$caption, margin_y = TRUE)
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caption_height <- grobHeight(caption)
@@ -261,6 +266,75 @@ ggplot_gtable.ggplot_built <- function(data) {
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plot_table <- gtable_add_grob(plot_table, caption, name = "caption",
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t = -1, b = -1, l = min(pans$l), r = max(pans$r), clip = "off")
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plot_table <- gtable_add_rows(plot_table, unit(0, 'pt'), pos = 0)
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plot_table <- gtable_add_cols(plot_table, unit(0, 'pt'), pos = 0)
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plot_table <- gtable_add_rows(plot_table, unit(0, 'pt'), pos = -1)
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plot_table <- gtable_add_cols(plot_table, unit(0, 'pt'), pos = -1)
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tag_pos <- theme$plot.tag.position
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if (length(tag_pos) == 2) tag_pos <- "manual"
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valid_pos <- c("topleft", "top", "topright", "left", "right", "bottomleft",
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"bottom", "bottomright")
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if (!(tag_pos == "manual" || tag_pos %in% valid_pos)) {
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stop("plot.tag.position should be a coordinate or one of ",
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paste(valid_pos, collapse = ', '), call. = FALSE)
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}
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if (tag_pos == "manual") {
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xpos <- theme$plot.tag.position[1]
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ypos <- theme$plot.tag.position[2]
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tag_parent <- justify_grobs(tag, x = xpos, y = ypos,
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hjust = theme$plot.tag$hjust,
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vjust = theme$plot.tag$vjust,
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debug = theme$plot.tag$debug)
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plot_table <- gtable_add_grob(plot_table, tag_parent, name = "tag", t = 1,
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b = nrow(plot_table), l = 1,
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r = ncol(plot_table), clip = "off")
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} else {
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# Widths and heights are reassembled below instead of assigning into them
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# in order to avoid bug in grid 3.2 and below.
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if (tag_pos == "topleft") {
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plot_table$widths <- unit.c(tag_width, plot_table$widths[-1])
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plot_table$heights <- unit.c(tag_height, plot_table$heights[-1])
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plot_table <- gtable_add_grob(plot_table, tag, name = "tag",
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t = 1, l = 1, clip = "off")
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} else if (tag_pos == "top") {
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plot_table$heights <- unit.c(tag_height, plot_table$heights[-1])
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plot_table <- gtable_add_grob(plot_table, tag, name = "tag",
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t = 1, l = 1, r = ncol(plot_table),
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clip = "off")
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} else if (tag_pos == "topright") {
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plot_table$widths <- unit.c(plot_table$widths[-ncol(plot_table)], tag_width)
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plot_table$heights <- unit.c(tag_height, plot_table$heights[-1])
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plot_table <- gtable_add_grob(plot_table, tag, name = "tag",
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t = 1, l = ncol(plot_table), clip = "off")
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} else if (tag_pos == "left") {
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plot_table$widths <- unit.c(tag_width, plot_table$widths[-1])
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plot_table <- gtable_add_grob(plot_table, tag, name = "tag",
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t = 1, b = nrow(plot_table), l = 1,
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clip = "off")
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} else if (tag_pos == "right") {
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plot_table$widths <- unit.c(plot_table$widths[-ncol(plot_table)], tag_width)
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plot_table <- gtable_add_grob(plot_table, tag, name = "tag",
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t = 1, b = nrow(plot_table), l = ncol(plot_table),
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clip = "off")
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} else if (tag_pos == "bottomleft") {
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plot_table$widths <- unit.c(tag_width, plot_table$widths[-1])
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plot_table$heights <- unit.c(plot_table$heights[-nrow(plot_table)], tag_height)
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plot_table <- gtable_add_grob(plot_table, tag, name = "tag",
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t = nrow(plot_table), l = 1, clip = "off")
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} else if (tag_pos == "bottom") {
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plot_table$heights <- unit.c(plot_table$heights[-nrow(plot_table)], tag_height)
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plot_table <- gtable_add_grob(plot_table, tag, name = "tag",
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t = nrow(plot_table), l = 1, r = ncol(plot_table), clip = "off")
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} else if (tag_pos == "bottomright") {
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plot_table$widths <- unit.c(plot_table$widths[-ncol(plot_table)], tag_width)
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plot_table$heights <- unit.c(plot_table$heights[-nrow(plot_table)], tag_height)
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plot_table <- gtable_add_grob(plot_table, tag, name = "tag",
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t = nrow(plot_table), l = ncol(plot_table), clip = "off")
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}
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}
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# Margins
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plot_table <- gtable_add_rows(plot_table, theme$plot.margin[1], pos = 0)
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plot_table <- gtable_add_cols(plot_table, theme$plot.margin[2])

‎R/theme-defaults.r‎

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@@ -188,6 +188,11 @@ theme_grey <- function(base_size = 11, base_family = "",
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hjust = 1, vjust = 1,
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margin = margin(t = half_line)
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),
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plot.tag = element_text(
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size = rel(1.2),
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hjust = 0.5, vjust = 0.5
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),
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plot.tag.position = 'topleft',
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plot.margin = margin(half_line, half_line, half_line, half_line),
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complete = TRUE
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hjust = 1, vjust = 1,
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margin = margin(t = half_line)
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),
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plot.tag = element_text(
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size = rel(1.2),
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hjust = 0.5, vjust = 0.5
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),
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plot.tag.position = 'topleft',
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complete = TRUE
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)
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hjust = 1, vjust = 1,
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margin = margin(t = half_line)
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),
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plot.tag = element_text(
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size = rel(1.2),
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hjust = 0.5, vjust = 0.5
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),
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plot.tag.position = 'topleft',
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plot.margin = margin(half_line, half_line, half_line, half_line),
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complete = TRUE

‎R/theme-elements.r‎

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@@ -345,6 +345,8 @@ el_def <- function(class = NULL, inherit = NULL, description = NULL) {
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plot.title = el_def("element_text", "title"),
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plot.subtitle = el_def("element_text", "title"),
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plot.caption = el_def("element_text", "title"),
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plot.tag = el_def("element_text", "title"),
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plot.tag.position = el_def("character"), # Need to also accept numbers
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plot.margin = el_def("margin"),
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aspect.ratio = el_def("character")

‎R/theme.r‎

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#' inherits from `title`) left-aligned by default
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#' @param plot.caption caption below the plot (text appearance)
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#' (`element_text`; inherits from `title`) right-aligned by default
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#' @param plot.tag upper-left label to identify a plot (text appearance)
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#' (`element_text`; inherits from `title`) left-aligned by default
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#' @param plot.tag.position The position of the tag as a string ("topleft",
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#' "top", "topright", "left", "right", "bottomleft", "bottom", "bottomright)
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#' or a coordinate. If a string, extra space will be added to accomodate the
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#' tag.
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#' @param plot.margin margin around entire plot (`unit` with the sizes of
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#' the top, right, bottom, and left margins)
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#'
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plot.title,
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plot.subtitle,
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plot.caption,
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plot.tag,
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plot.tag.position,
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plot.margin,
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strip.background,
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strip.background.x,

‎man/theme.Rd‎

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‎tests/figs/labels/defaults.svg‎

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