ggplot2:在facet中创建facet

Question

我不知道我是否正确地表达了自己的标题，但我希望这是容易理解，当你看到以下数字。首先，这是我的数据：

hydrocarbons    average SD  type    group
N   6,21    4,632774217 PAHs    Naphtalenes
N1  4,71    2,43670665  PAHs    Naphtalenes
N2  7,6 3,266286228 PAHs    Naphtalenes
N3  16,18   11,00643289 PAHs    Naphtalenes
N4  18,8    4,59631824  PAHs    Naphtalenes
F   16,87   7,022165062 PAHs    Fluorenes
F1  16,64   5,721267073 PAHs    Fluorenes
F2  18,67   8,467132345 PAHs    Fluorenes
F3  22,79   0,988021105 PAHs    Fluorenes
P   7,97    0,211647391 PAHs    Phenanthrenes
P1  26,66   16,64819987 PAHs    Phenanthrenes
P2  21,72   4,416811664 PAHs    Phenanthrenes
P3  18,99   4,635405486 PAHs    Phenanthrenes
P4  66,28   7,706085861 PAHs    Phenanthrenes
D   8,33    0,89862145  PAHs    Dibenzothiophenes
D1  8,63        PAHs    Dibenzothiophenes
D2  9,57        PAHs    Dibenzothiophenes
D3  20,69   3,453922632 PAHs    Dibenzothiophenes
D4  32,5    8,191613185 PAHs    Dibenzothiophenes
FL  10,37       PAHs    Fluoranthenes
PY  10,53       PAHs    Fluoranthenes
FL1 24,42   8,886055918 PAHs    Fluoranthenes
FL2 42,52   9,466539232 PAHs    Fluoranthenes
FL3 51,99   15,77786373 PAHs    Fluoranthenes
C   74,28   9,560499532 PAHs    Chrysenes
C1  46,56   15,86163409 PAHs    Chrysenes
C2  82,85   4,854714782 PAHs    Chrysenes
C3  114,42  41,70884318 PAHs    Chrysenes
nC-10   2,24        alkanes 
nC-11   2,24        alkanes 
nC-12   4,85    1,414267191 alkanes 
nC-13   5,54    0,089306765 alkanes 
nC-14   6,81    0,241222891 alkanes 
nC-15   5,56        alkanes 
nC-16   5,95        alkanes 
nC-17   5,82        alkanes 
nC-18   5,7     alkanes 
nC-19   6,41        alkanes 
nC-20   7,36        alkanes 
nC-21   6,24        alkanes 
nC-22   6,07        alkanes 
nC-23   6,35        alkanes 
nC-24   7,32        alkanes 
nC-25   6,6 2,215395794 alkanes 
nC-26   5,97    1,839829721 alkanes 
nC-27   6,51    1,972060107 alkanes 
nC-28   7,57    1,797509743 alkanes 
nC-29   8,37    3,004883333 alkanes 
nC-30   9,05    3,503601406 alkanes 
nC-31   10,27   4,242811665 alkanes 
nC-32   11,5    5,087821955 alkanes 
nC-33   14,31   8,085948386 alkanes 
nC-34   16,96   10,10105484 alkanes 
nC-35   20,52   14,1878649  alkanes 
nC-36   21,88   13,40071226 alkanes 
n-C5 (Pentane)  10,63   1,715015757 VOCs    
n-C6 (Hexane)   1,74    0,859880844 VOCs    
n-C7 (Heptane)  9,62    4,316473516 VOCs    
n-C9 (Nonane)   2,34    0,044641    VOCs    
Benzene 23,51   0,631882255 VOCs    
Toluene 18,48   2,369137637 VOCs    
Ethylbenzene    7,55    7,171631537 VOCs    
m-Xylene    12,53   7,250491275 VOCs    
p-Xylene    15,21   1,800247445 VOCs    
o-Xylene    21,96   2,184177383 VOCs    
Propylbenzene   12,8    15,31136895 VOCs    
n-Butylbenzene  9,33    5,486543125 VOCs    
n-Pentylbenzene 6,77    0,420247353 VOCs

我想绘制我的碳氢化合物的半衰期(“平均”)，并按“类型”对其进行分类。然而，只有类型"PAHs“，我想有额外的方面，根据”组“。我能编写的最好的代码和图是下面的图，但这并不完全是我想要的：

​

这是我使用的代码：

all <- read.delim2("E#6-results_chemistry.txt", header=TRUE)
library(ggplot2)
all$hydrocarbons <- factor(all$hydrocarbons, levels = all$hydrocarbons) #keeps the order of x-axis same as in table
levels(all$type)[levels(all$type)=="alkanes"] <- "n-alkanes" #if needed to change specific labels in a column
ggplot(all, aes(x=hydrocarbons, y=average)) +
  geom_bar(position = position_dodge(), stat="identity", fill="gray32") + 
  geom_errorbar(aes(ymin=average-SD, ymax=average+SD), color="gray8") + 
  facet_wrap(~type, scales="free", ncol=1) +
  ylab("Half-life [d]") + xlab("Hydrocarbons") +
  theme(axis.text.x=element_text(size=12, color="black", angle=45, hjust=1),
axis.title.x = element_text(size=14, face="bold", vjust=-0.7), 
axis.title.y = element_text(size=14, face="bold", vjust=2),
axis.text.y = element_text(size=12, colour="black"))

现在，问题是，是否有可能制作一个图形，我可以在现有的一个，只为"PAHs“类型，根据”组“额外的小面条？图形看起来应该是这样的：

​

如果可能的话，它也适用于我，为"PAHs“做第二个x轴，然后按照”群组“排列它。

谢谢你，丹尼斯

Answer 1

我想你需要深入研究ggplot的结构。这种方法采用了原来的情节，但去掉了中间面板(但保留了空间)。我将中间面板作为一个单独的图来构造，包括“PAHs”级别的各个方面。我从这个图中提取相关的材料(地块、条形、x轴和y轴)，将其插入到原图中的空空间中。然后，构造一个包含变量名称“PAHs”的新条。该方法确保三个面板的高度相同，unit(1, "null")。(请参阅下面我使用的all数据框架的图表。)

次要编辑:更新到ggplot2 2.2.1

library(ggplot2)
library(gtable)
library(grid)
all$hydrocarbons <- factor(all$hydrocarbons, levels = all$hydrocarbons) #keeps the order of x-axis same as in table
   levels(all$type)[levels(all$type)=="alkanes"] <- "n-alkanes" #if needed to change specific labels in a column

# Original plot
pAll <- ggplot(all, aes(x = hydrocarbons, y = average)) +
  geom_bar(position = position_dodge(), stat="identity", fill = "gray32") + 
  geom_errorbar(aes(ymin = average-SD, ymax = average+SD), color = "gray8") + 
  facet_wrap( ~ type, scales = "free", ncol = 1) +
  ylab("Half-life [d]") + xlab("Hydrocarbons") +
  theme(axis.text.x = element_text(size = 12, color = "black", angle = 45, hjust = 1),
     axis.title.x = element_text(size = 14, face = "bold", vjust = -0.7), 
     axis.title.y = element_text(size = 14, face = "bold", vjust = 2),
     axis.text.y = element_text(size = 12, colour = "black"))

# Middle plot, but with facets for 'PAHs'
pMid <- ggplot(subset(all, type == "PAHs"), aes(x = hydrocarbons, y = average)) +
  geom_bar(position = position_dodge(), stat = "identity", fill = "gray32") + 
  geom_errorbar(aes(ymin = average - SD, ymax = average + SD), color = "gray8") + 
  facet_grid(. ~ group, scales = "free", space = "free") +
  ylab("Half-life [d]") + 
  theme(axis.text.x = element_text(size = 12, color = "black", angle = 45, hjust = 1),
     axis.title.x = element_text(size = 14, face = "bold", vjust = -0.7), 
     axis.title.y = element_text(size = 14, face = "bold", vjust = 2),
     axis.text.y = element_text(size = 12, colour = "black"))

# Get the ggplot grobs
gAll <- ggplotGrob(pAll)
gMid <- ggplotGrob(pMid)

# In gMid, get the positions of the panels in the layout: t = top, l = left, ...
pos1 <- c(subset(gMid$layout, grepl("panel", gMid$layout$name), select = t:r))

# Extract 'panels' (along with x-axis and strips)
panels <- gMid[(unique(pos1$t) - 1) : (unique(pos1$t) + 1), min(pos1$l) : max(pos1$l)]
# Extract 'axisL' - y-axis
axisL <- gMid[unique(pos1$t), min(pos1$l) - 1]

# In gAll, get the positions of the panel of the middle plot in the layout
pos2 <- c(subset(gAll$layout, grepl("panel", gAll$layout$name), select = t:r))
pos2 <- lapply(pos2, "[", 2)

# Drop original panel material in the middle plot
drop <- gAll$layout$name %in% c("panel-1-2", "strip-t-1-2", "axis-b-1-2", "axis-l-2-1")
gAll$grobs[drop] <- NULL
gAll$layout <- gAll$layout[!drop,]

# Add new 'panels' to gAll
gAll <- gtable_add_grob(gAll, panels, t = pos2$t-1, l = pos2$l, b = pos2$t+1,  name = "panels")

# Add new 'axisL' to gAll
gAll <- gtable_add_grob(gAll, axisL, t = pos2$t, l = pos2$l-1, name = "strips")

# Add row above the current strips
gAll <- gtable_add_rows(gAll, gAll$heights[pos2$t-1], pos2$t-2)  

# Add grob, a new strip containing variable name 'PAHs', into the new row
gAll <- gtable_add_grob(gAll, 
  list(rectGrob(gp = gpar(col = NA, fill = "gray85")),
       textGrob("PAHs", gp = gpar(fontsize = 9.6))), 
  t = pos2$t-1, l = pos2$l, name = c("background", "text"))

# Add a small gap between the strips
gAll <- gtable_add_rows(gAll, unit(1/10, "line"), pos2$t-1)

# Probably not needed, but if axisB font size in pMid is different from pAll
gAll$heights[pos2$t + 3] <- gMid$heights[unique(pos1$t) + 1]

# Draw it
grid.newpage()
grid.draw(gAll)

​

​

all = structure(list(hydrocarbons = structure(c(21L, 28L, 29L, 30L, 
31L, 12L, 13L, 14L, 15L, 60L, 62L, 63L, 64L, 65L, 6L, 7L, 8L, 
9L, 10L, 16L, 67L, 17L, 18L, 19L, 2L, 3L, 4L, 5L, 32L, 33L, 34L, 
35L, 36L, 37L, 38L, 39L, 40L, 41L, 42L, 43L, 44L, 45L, 46L, 47L, 
48L, 49L, 50L, 51L, 52L, 53L, 54L, 55L, 56L, 57L, 58L, 23L, 24L, 
25L, 26L, 1L, 68L, 11L, 20L, 61L, 59L, 66L, 22L, 27L), .Label = c("Benzene", 
"C", "C1", "C2", "C3", "D", "D1", "D2", "D3", "D4", "Ethylbenzene", 
"F", "F1", "F2", "F3", "FL", "FL1", "FL2", "FL3", "m-Xylene", 
"N", "n-Butylbenzene", "n-C5 (Pentane)", "n-C6 (Hexane)", "n-C7 (Heptane)", 
"n-C9 (Nonane)", "n-Pentylbenzene", "N1", "N2", "N3", "N4", "nC-10", 
"nC-11", "nC-12", "nC-13", "nC-14", "nC-15", "nC-16", "nC-17", 
"nC-18", "nC-19", "nC-20", "nC-21", "nC-22", "nC-23", "nC-24", 
"nC-25", "nC-26", "nC-27", "nC-28", "nC-29", "nC-30", "nC-31", 
"nC-32", "nC-33", "nC-34", "nC-35", "nC-36", "o-Xylene", "P", 
"p-Xylene", "P1", "P2", "P3", "P4", "Propylbenzene", "PY", "Toluene"
), class = "factor"), average = c(6.21, 4.71, 7.6, 16.18, 18.8, 
16.87, 16.64, 18.67, 22.79, 7.97, 26.66, 21.72, 18.99, 66.28, 
8.33, 8.63, 9.57, 20.69, 32.5, 10.37, 10.53, 24.42, 42.52, 51.99, 
74.28, 46.56, 82.85, 114.42, 2.24, 2.24, 4.85, 5.54, 6.81, 5.56, 
5.95, 5.82, 5.7, 6.41, 7.36, 6.24, 6.07, 6.35, 7.32, 6.6, 5.97, 
6.51, 7.57, 8.37, 9.05, 10.27, 11.5, 14.31, 16.96, 20.52, 21.88, 
10.63, 1.74, 9.62, 2.34, 23.51, 18.48, 7.55, 12.53, 15.21, 21.96, 
12.8, 9.33, 6.77), SD = c(4.632774217, 2.43670665, 3.266286228, 
11.00643289, 4.59631824, 7.022165062, 5.721267073, 8.467132345, 
0.988021105, 0.211647391, 16.64819987, 4.416811664, 4.635405486, 
7.706085861, 0.89862145, NA, NA, 3.453922632, 8.191613185, NA, 
NA, 8.886055918, 9.466539232, 15.77786373, 9.560499532, 15.86163409, 
4.854714782, 41.70884318, NA, NA, 1.414267191, 0.089306765, 0.241222891, 
NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, 2.215395794, 1.839829721, 
1.972060107, 1.797509743, 3.004883333, 3.503601406, 4.242811665, 
5.087821955, 8.085948386, 10.10105484, 14.1878649, 13.40071226, 
1.715015757, 0.859880844, 4.316473516, 0.044641, 0.631882255, 
2.369137637, 7.171631537, 7.250491275, 1.800247445, 2.184177383, 
15.31136895, 5.486543125, 0.420247353), type = structure(c(2L, 
2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 
2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 1L, 1L, 1L, 1L, 1L, 
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
1L, 1L, 1L, 1L, 1L, 1L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 
3L, 3L, 3L), .Label = c("alkanes", "PAHs", "VOCs"), class = "factor"), 
    group = structure(c(6L, 6L, 6L, 6L, 6L, 5L, 5L, 5L, 5L, 7L, 
    7L, 7L, 7L, 7L, 3L, 3L, 3L, 3L, 3L, 4L, 4L, 4L, 4L, 4L, 2L, 
    2L, 2L, 2L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
    1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
    1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L), .Label = c("", 
    "Chrysenes", "Dibenzothiophenes", "Fluoranthenes", "Fluorenes", 
    "Naphtalenes", "Phenanthrenes"), class = "factor")), .Names = c("hydrocarbons", 
"average", "SD", "type", "group"), class = "data.frame", row.names = c(NA, 
-68L))