Как я могу показать пользовательскую аннотацию только один раз на граненом ggplot2?

Question

Я создал граненый график в ggplot2 (см. Рисунок выше), в который я хотел бы добавить дополнительную легенду, чтобы указать алфавитный указатель, который у меня естьиспользуется на осях X и Y графика в дополнение к показанной цветовой легенде.

Мне удалось сделать это, используя annotation_custom, но аннотация появлялась 6 раз, по одному разу на каждом фасете.Я хочу разместить его только один раз под индексом цветовой шкалы.См. Изображение ниже.

Мой код для ggplot2 приведен ниже

library(ggplot2)
corrma <- ggplot(samelt, aes(x = Var1, y = Var2, fill = value)) +
  geom_tile(color = "white") +
  scale_fill_gradient2(low = "steelblue", high = "tomato2", 
                       mid = "white",  
                       midpoint = 0,
                       limit = c(-1,1)) +
  theme_minimal() +
  scale_y_discrete(labels = s3) +
  scale_x_discrete(labels = s3) +
  coord_fixed() +
  facet_wrap( ~ Country, nrow = 2) +
  labs(title = "Correlation Matrix of South Asian Indicators") +
  theme(legend.direction = "horizontal")+
  theme(plot.margin = unit(c(0,0,0,0), "cm")) 

text <- paste(  "a - Age_dpdn_ratio_wkpop\n",
                "b - Birth_rt\n",
                "c - Death_rt\n",
                "d - Fertility_rt\n",
                "e - Health_exp_pcofGDP\n",
                "f - Life_exp\n",
                "g - Private_hlth_exp_pc_oftotal\n",
                "h - ruralpop_drnkwater_pc", sep = " ")

text.p <- ggparagraph(text = text, face = "italic", size = 8, color = "black")

corrma + annotation_custom(ggplotGrob(text.p))

После нескольких испытаний я обнаружил, что cowplot дает ближайший возможныйрешение.Фигура этого приведена ниже..Добавленная кодовая строка выглядит следующим образом.Кроме того, чтобы упомянуть здесь, что поля сюжета также были обрезаны.

library(cowplot)
plot_grid(corma, text.p, nrow = 2, ncol=1, align= "v", axis = "l", rel_widths = c(1, .1), rel_heights = c(1, .1))

Я думаю, это может быть только временное решение.

structure(list(Var1 = structure(c(1L, 2L, 3L, 4L, 5L, 6L, 7L, 
8L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 3L, 4L, 5L, 6L, 7L, 8L, 4L, 5L, 
6L, 7L, 8L, 5L, 6L, 7L, 8L, 6L, 7L, 8L, 7L, 8L, 8L, 1L, 2L, 3L, 
4L, 5L, 6L, 7L, 8L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 3L, 4L, 5L, 6L, 
7L, 8L, 4L, 5L, 6L, 7L, 8L, 5L, 6L, 7L, 8L, 6L, 7L, 8L, 7L, 8L, 
8L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 
3L, 4L, 5L, 6L, 7L, 8L, 4L, 5L, 6L, 7L, 8L, 5L, 6L, 7L, 8L, 6L, 
7L, 8L, 7L, 8L, 8L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 2L, 3L, 4L, 
5L, 6L, 7L, 8L, 3L, 4L, 5L, 6L, 7L, 8L, 4L, 5L, 6L, 7L, 8L, 5L, 
6L, 7L, 8L, 6L, 7L, 8L, 7L, 8L, 8L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 
8L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 3L, 4L, 5L, 6L, 7L, 8L, 4L, 5L, 
6L, 7L, 8L, 5L, 6L, 7L, 8L, 6L, 7L, 8L, 7L, 8L, 8L, 1L, 2L, 3L, 
4L, 5L, 6L, 7L, 8L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 3L, 4L, 5L, 6L, 
7L, 8L, 4L, 5L, 6L, 7L, 8L, 5L, 6L, 7L, 8L, 6L, 7L, 8L, 7L, 8L, 
8L), .Label = c("ruralpop_drnkwater_pc", "Life_exp", "Fertility_rt", 
"Private_hlth_exp_pc_oftotal", "Death_rt", "Health_exp_pcofGDP", 
"Birth_rt", "Age_dpdn_ratio_wkpop"), class = "factor"), Var2 = structure(c(1L, 
1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 
3L, 3L, 3L, 3L, 4L, 4L, 4L, 4L, 4L, 5L, 5L, 5L, 5L, 6L, 6L, 6L, 
7L, 7L, 8L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 
2L, 2L, 3L, 3L, 3L, 3L, 3L, 3L, 4L, 4L, 4L, 4L, 4L, 5L, 5L, 5L, 
5L, 6L, 6L, 6L, 7L, 7L, 8L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 
2L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L, 3L, 3L, 4L, 4L, 4L, 4L, 
4L, 5L, 5L, 5L, 5L, 6L, 6L, 6L, 7L, 7L, 8L, 1L, 1L, 1L, 1L, 1L, 
1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L, 3L, 3L, 
4L, 4L, 4L, 4L, 4L, 5L, 5L, 5L, 5L, 6L, 6L, 6L, 7L, 7L, 8L, 1L, 
1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 
3L, 3L, 3L, 3L, 4L, 4L, 4L, 4L, 4L, 5L, 5L, 5L, 5L, 6L, 6L, 6L, 
7L, 7L, 8L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 
2L, 2L, 3L, 3L, 3L, 3L, 3L, 3L, 4L, 4L, 4L, 4L, 4L, 5L, 5L, 5L, 
5L, 6L, 6L, 6L, 7L, 7L, 8L), .Label = c("ruralpop_drnkwater_pc", 
"Life_exp", "Fertility_rt", "Private_hlth_exp_pc_oftotal", "Death_rt", 
"Health_exp_pcofGDP", "Birth_rt", "Age_dpdn_ratio_wkpop"), class = "factor"), 
    value = c(1, 1, -1, -0.79, -1, -0.98, -1, -1, 1, -1, -0.79, 
    -1, -0.98, -1, -1, 1, 0.8, 1, 0.98, 1, 1, 1, 0.76, 0.77, 
    0.82, 0.78, 1, 0.98, 1, 1, 1, 0.97, 0.98, 1, 1, 1, 1, 1, 
    -0.98, 0.63, -1, -0.48, -0.82, -0.99, 1, -0.97, 0.59, -0.99, 
    -0.53, -0.8, -0.98, 1, -0.7, 0.99, 0.38, 0.92, 0.99, 1, -0.64, 
    0.21, -0.72, -0.73, 1, 0.47, 0.87, 0.99, 1, 0.17, 0.36, 1, 
    0.89, 1, 1, 1, -0.99, 0.87, -0.99, 0.56, -1, -1, 1, -1, 0.88, 
    -1, 0.56, -1, -1, 1, -0.89, 1, -0.55, 1, 1, 1, -0.89, 0.37, 
    -0.88, -0.88, 1, -0.56, 1, 1, 1, -0.55, -0.58, 1, 1, 1, 1, 
    1, -1, 0.58, -0.98, 0.64, -1, -0.98, 1, -1, 0.54, -1, 0.62, 
    -1, -0.95, 1, -0.57, 0.99, -0.63, 1, 0.97, 1, -0.48, 0.41, 
    -0.58, -0.68, 1, -0.6, 0.99, 0.92, 1, -0.64, -0.67, 1, 0.97, 
    1, 1, 0.99, -0.99, 0.74, -0.97, -0.89, -0.99, -0.99, 1, -1, 
    0.79, -0.99, -0.91, -1, -1, 1, -0.8, 0.99, 0.91, 1, 1, 1, 
    -0.84, -0.77, -0.8, -0.82, 1, 0.92, 0.99, 1, 1, 0.91, 0.91, 
    1, 1, 1, 1, 0.93, -0.52, 0.89, -0.47, -0.9, -0.78, 0.02, 
    1, -0.18, 0.69, -0.77, -0.76, -0.5, -0.34, 1, -0.71, -0.44, 
    0.7, 0.94, -0.79, 1, -0.1, -0.82, -0.89, 0.29, 1, 0.25, -0.14, 
    0.84, 1, 0.87, -0.24, 1, -0.59, 1), Country = c("India", 
    "India", "India", "India", "India", "India", "India", "India", 
    "India", "India", "India", "India", "India", "India", "India", 
    "India", "India", "India", "India", "India", "India", "India", 
    "India", "India", "India", "India", "India", "India", "India", 
    "India", "India", "India", "India", "India", "India", "India", 
    "Pakistan", "Pakistan", "Pakistan", "Pakistan", "Pakistan", 
    "Pakistan", "Pakistan", "Pakistan", "Pakistan", "Pakistan", 
    "Pakistan", "Pakistan", "Pakistan", "Pakistan", "Pakistan", 
    "Pakistan", "Pakistan", "Pakistan", "Pakistan", "Pakistan", 
    "Pakistan", "Pakistan", "Pakistan", "Pakistan", "Pakistan", 
    "Pakistan", "Pakistan", "Pakistan", "Pakistan", "Pakistan", 
    "Pakistan", "Pakistan", "Pakistan", "Pakistan", "Pakistan", 
    "Pakistan", "Bangladesh", "Bangladesh", "Bangladesh", "Bangladesh", 
    "Bangladesh", "Bangladesh", "Bangladesh", "Bangladesh", "Bangladesh", 
    "Bangladesh", "Bangladesh", "Bangladesh", "Bangladesh", "Bangladesh", 
    "Bangladesh", "Bangladesh", "Bangladesh", "Bangladesh", "Bangladesh", 
    "Bangladesh", "Bangladesh", "Bangladesh", "Bangladesh", "Bangladesh", 
    "Bangladesh", "Bangladesh", "Bangladesh", "Bangladesh", "Bangladesh", 
    "Bangladesh", "Bangladesh", "Bangladesh", "Bangladesh", "Bangladesh", 
    "Bangladesh", "Bangladesh", "Nepal", "Nepal", "Nepal", "Nepal", 
    "Nepal", "Nepal", "Nepal", "Nepal", "Nepal", "Nepal", "Nepal", 
    "Nepal", "Nepal", "Nepal", "Nepal", "Nepal", "Nepal", "Nepal", 
    "Nepal", "Nepal", "Nepal", "Nepal", "Nepal", "Nepal", "Nepal", 
    "Nepal", "Nepal", "Nepal", "Nepal", "Nepal", "Nepal", "Nepal", 
    "Nepal", "Nepal", "Nepal", "Nepal", "Bhutan", "Bhutan", "Bhutan", 
    "Bhutan", "Bhutan", "Bhutan", "Bhutan", "Bhutan", "Bhutan", 
    "Bhutan", "Bhutan", "Bhutan", "Bhutan", "Bhutan", "Bhutan", 
    "Bhutan", "Bhutan", "Bhutan", "Bhutan", "Bhutan", "Bhutan", 
    "Bhutan", "Bhutan", "Bhutan", "Bhutan", "Bhutan", "Bhutan", 
    "Bhutan", "Bhutan", "Bhutan", "Bhutan", "Bhutan", "Bhutan", 
    "Bhutan", "Bhutan", "Bhutan", "Sri Lanka", "Sri Lanka", "Sri Lanka", 
    "Sri Lanka", "Sri Lanka", "Sri Lanka", "Sri Lanka", "Sri Lanka", 
    "Sri Lanka", "Sri Lanka", "Sri Lanka", "Sri Lanka", "Sri Lanka", 
    "Sri Lanka", "Sri Lanka", "Sri Lanka", "Sri Lanka", "Sri Lanka", 
    "Sri Lanka", "Sri Lanka", "Sri Lanka", "Sri Lanka", "Sri Lanka", 
    "Sri Lanka", "Sri Lanka", "Sri Lanka", "Sri Lanka", "Sri Lanka", 
    "Sri Lanka", "Sri Lanka", "Sri Lanka", "Sri Lanka", "Sri Lanka", 
    "Sri Lanka", "Sri Lanka", "Sri Lanka")), .Names = c("Var1", 
"Var2", "value", "Country"), row.names = c("1", "2", "3", "4", 
"5", "6", "7", "8", "10", "11", "12", "13", "14", "15", "16", 
"19", "20", "21", "22", "23", "24", "28", "29", "30", "31", "32", 
"37", "38", "39", "40", "46", "47", "48", "55", "56", "64", "17", 
"25", "33", "41", "51", "61", "71", "81", "101", "111", "121", 
"131", "141", "151", "161", "191", "201", "211", "221", "231", 
"241", "281", "291", "301", "311", "321", "371", "381", "391", 
"401", "461", "471", "481", "551", "561", "641", "18", "26", 
"34", "42", "52", "62", "72", "82", "102", "112", "122", "132", 
"142", "152", "162", "192", "202", "212", "222", "232", "242", 
"282", "292", "302", "312", "322", "372", "382", "392", "402", 
"462", "472", "482", "552", "562", "642", "110", "27", "35", 
"43", "53", "63", "73", "83", "103", "113", "123", "133", "143", 
"153", "163", "193", "203", "213", "223", "233", "243", "283", 
"293", "303", "313", "323", "373", "383", "393", "403", "463", 
"473", "483", "553", "563", "643", "114", "210", "36", "44", 
"54", "65", "74", "84", "104", "115", "124", "134", "144", "154", 
"164", "194", "204", "214", "224", "234", "244", "284", "294", 
"304", "314", "324", "374", "384", "394", "404", "464", "474", 
"484", "554", "564", "644", "116", "215", "310", "45", "57", 
"66", "75", "85", "105", "117", "125", "135", "145", "155", "165", 
"195", "205", "216", "225", "235", "245", "285", "295", "305", 
"315", "325", "375", "385", "395", "405", "465", "475", "485", 
"555", "565", "645"), class = "data.frame")

Answer 1

Вы можете попробовать egg::geom_custom()

d <- data.frame(vs = 1, x=30, y=300)
d$grob <- list(grid::textGrob('test'))
ggplot(mtcars, aes(mpg,disp)) + facet_wrap(~vs) + geom_point() +
  egg::geom_custom(data = d, aes(x,y,data=grob), grob_fun = identity,
                   inherit.aes = F)

Answer 2

Я не уверен, есть ли способ достичь того, что вы хотите, используя автоматически сгенерированную легенду.Краткое описание проблемы: для того, чтобы это работало, должно быть отображение от некоторых geom_* до значений в данных, что не соответствует вашему примеру.

Возможно, есть более элегантный способ сделать этоно вот пример, который использует ggplotGrob() и annotation_custom() вместе с grid::grid.draw():

Идея здесь состоит в том, чтобы разместить внешний графический элемент, называемый grob (в данном случаеаннотации), в ggplot2.Я использую числовые столбцы в наборе данных mpg в примере ниже, поскольку вы не предоставили никаких данных.Обратите внимание, что я немного изменил ваш код (обоснование легенды о цветовом градиенте):

# long format of the numeric columns in `mpg`
d <- cor(mpg %> % select_if(is.numeric)) %> % reshape2::melt()

# axis labels
s3 <- c("a", "b", "c", "d", "e")

# legend keys
labs <- c("a - engine displacement\nb - year of manufacture\nc - number of cylinders\nd - city miles per gallon\ne - highway miles per gallon")

p <- ggplot(data = d) +
     geom_tile(aes(x = Var1, y = Var2, fill = value), color = "white") +
     scale_fill_gradient2(low = "steelblue", high = "tomato2",
        mid = "white",
        midpoint = 0,
        limit = c(-1, 1)) +
     theme_minimal() +
     scale_y_discrete(labels = s3) +
     scale_x_discrete(labels = s3) +
     theme(legend.direction = "horizontal", legend.justification = "top") +
     labs(fill = "Pearson\nCoefficient")

Добавьте аннотацию, добавив

+ annotation_custom(textGrob(label = labs, just = "left",
                           gp = gpar(fontsize = 11)), 
                  ymin = 1, ymax = 4, xmin = 6.5)

к приведенному выше.Затем сгенерируйте ggplot2 grob, отключите отсечение и нарисуйте результат.

g <- ggplotGrob(p)
g$layout$clip[g$layout$name == "panel"] <- "off"
grid::grid.draw(g)