ggplot2 — добавление вторичной оси Y поверх графика

Обновлен до ggplot2 версии 2.2.1, но использовать sec.axis проще — см. здесь

Исходный

Начиная с ggplot2 версии 2.1.0, процесс перемещения осей стал намного сложнее, причина в том, что метки стали сложными гробами, содержащими текстовые гробы и поля. (Есть также ошибка с axis.line. Временный обходной путь — установить линии оси X и оси Y отдельно.)

Решение основано на более старых решениях, которые работают со старыми версиями ggplot, и на функции cowplot для копирования и перемещения осей. Но имейте в виду, что решение может не работать с будущими версиями ggplot2.

Я использовал составленные данные из старого решения. В примере показаны две шкалы, измеряющие одно и то же — футы и метры.

library(ggplot2) # v 2.2.1
library(gtable)  # v 0.2.0
library(grid)

df <- data.frame(Day = c(1:365), Elevation = sin(seq(0, 2 * pi, 2 * pi / 364)) * 10 + 100)

p1 <- ggplot(data = df) + 
        geom_line(aes(x = Day,y = Elevation)) + 
        scale_y_continuous(name = "Elevation (m)", limits = c(75, 125)) +
        theme_bw(base_size = 12, base_family = "Helvetica") + 
        theme(panel.grid = element_blank()) +
        theme( # Increase size of axis lines
          axis.line.x = element_line(size = .7, color = "black"),
          axis.line.y = element_line(size = .7, color = "black"),
          panel.border = element_blank())


p2 <- ggplot(data = df)+
        geom_line(aes(x = Day, y = Elevation))+
        scale_y_continuous(name = "Elevation (ft)", limits = c(75, 125),           
          breaks=c(80, 90, 100, 110, 120),
          labels=c("262", "295", "328", "361", "394")) +
        theme_bw(base_size = 12, base_family = "Helvetica") + 
        theme(panel.grid = element_blank()) +
        theme( # Increase size of axis lines
          axis.line.x = element_line(size = .7, color = "black"),
          axis.line.y = element_line(size = .7, color = "black"),
          panel.border = element_blank())


# Get the ggplot grobs
g1 <- ggplotGrob(p1)
g2 <- ggplotGrob(p2)

# Get the location of the plot panel in g1.
# These are used later when transformed elements of g2 are put back into g1
pp <- c(subset(g1$layout, name == "panel", se = t:r))

# ggplot contains many labels that are themselves complex grob; 
# usually a text grob surrounded by margins.
# When moving the grobs from, say, the left to the right of a plot,
# make sure the margins and the justifications are swapped around.
# The function below does the swapping.
# Taken from the cowplot package:
# https://github.com/wilkelab/cowplot/blob/master/R/switch_axis.R 

hinvert_title_grob <- function(grob){

  # Swap the widths
  widths <- grob$widths
  grob$widths[1] <- widths[3]
  grob$widths[3] <- widths[1]
  grob$vp[[1]]$layout$widths[1] <- widths[3]
  grob$vp[[1]]$layout$widths[3] <- widths[1]

  # Fix the justification
  grob$children[[1]]$hjust <- 1 - grob$children[[1]]$hjust 
  grob$children[[1]]$vjust <- 1 - grob$children[[1]]$vjust 
  grob$children[[1]]$x <- unit(1, "npc") - grob$children[[1]]$x
  grob
}

# Get the y axis title from g2 - "Elevation (ft)" 
index <- which(g2$layout$name == "ylab-l") # Which grob contains the y axis title?
ylab <- g2$grobs[[index]]                # Extract that grob
ylab <- hinvert_title_grob(ylab)         # Swap margins and fix justifications

# Put the transformed label on the right side of g1
g1 <- gtable_add_cols(g1, g2$widths[g2$layout[index, ]$l], pp$r)
g1 <- gtable_add_grob(g1, ylab, pp$t, pp$r + 1, pp$b, pp$r + 1, clip = "off", name = "ylab-r")

# Get the y axis from g2 (axis line, tick marks, and tick mark labels)
index <- which(g2$layout$name == "axis-l")  # Which grob
yaxis <- g2$grobs[[index]]                  # Extract the grob

# yaxis is a complex of grobs containing the axis line, the tick marks, and the tick mark labels.
# The relevant grobs are contained in axis$children:
#   axis$children[[1]] contains the axis line;
#   axis$children[[2]] contains the tick marks and tick mark labels.

# First, move the axis line to the left
yaxis$children[[1]]$x <- unit.c(unit(0, "npc"), unit(0, "npc"))

# Second, swap tick marks and tick mark labels
ticks <- yaxis$children[[2]]
ticks$widths <- rev(ticks$widths)
ticks$grobs <- rev(ticks$grobs)

# Third, move the tick marks
ticks$grobs[[1]]$x <- ticks$grobs[[1]]$x - unit(1, "npc") + unit(3, "pt")

# Fourth, swap margins and fix justifications for the tick mark labels
ticks$grobs[[2]] <- hinvert_title_grob(ticks$grobs[[2]])

# Fifth, put ticks back into yaxis
yaxis$children[[2]] <- ticks

# Put the transformed yaxis on the right side of g1
g1 <- gtable_add_cols(g1, g2$widths[g2$layout[index, ]$l], pp$r)
g1 <- gtable_add_grob(g1, yaxis, pp$t, pp$r + 1, pp$b, pp$r + 1, clip = "off", name = "axis-r")

# Draw it
grid.newpage()
grid.draw(g1)

Второй пример показывает, как включить два разных масштаба. Но имейте в виду, что здесь есть что критиковать: -и-другая-ось-y-справа/3101876#3101876">отдельные шкалы Y и сюжеты с динамитом

df1 <- structure(list(month = structure(1:12, .Label = c("Apr", "Aug", 
"Dec", "Feb", "Jan", "Jul", "Jun", "Mar", "May", "Nov", "Oct", 
"Sep"), class = "factor"), RI = c(0.52, 0.115, 0.636666666666667, 
0.807, 0.66625, 0.34, 0.143333333333333, 0.58375, 0.173333333333333, 
0.5, 0.13, 0), sd = c(0.327566787083184, 0.162634559672906, 0.299555225848813, 
0.172887246493199, 0.293010848165827, 0.480832611206852, 0.222785397486759, 
0.381610777775321, 0.219393102292058, 0.3, 0.183847763108502, 
0)), .Names = c("month", "RI", "sd"), class = "data.frame", row.names = c(NA, 
-12L))

df2<-structure(list(month = structure(c(5L, 4L, 8L, 1L, 9L, 7L, 6L, 
2L, 12L, 11L, 10L, 3L), .Label = c("Apr", "Aug", "Dec", "Feb", 
"Jan", "Jul", "Jun", "Mar", "May", "Nov", "Oct", "Sep"), class = "factor"), 
    temp = c(25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25)), .Names = c("month", 
"temp"), row.names = c(NA, -12L), class = "data.frame")

library(ggplot2)
library(gtable)
library(grid)

p1 <-
  ggplot(data = df1, aes(x=month,y=RI)) + 
  geom_errorbar(aes(ymin=0,ymax=RI+sd),width=0.2,color="grey") +
  geom_bar(width=0.5,stat="identity",position=position_dodge(), fill = "grey") +
  scale_y_continuous(limits=c(0,1),expand = c(0,0)) +  scale_x_discrete(limits=c("Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec")) +
  theme_bw(base_size = 12, base_family = "Helvetica") + 
  theme(panel.grid = element_blank()) +
  theme( # Increase size of axis lines
    axis.line.x = element_line(size = .7, color = "black"),
    axis.line.y = element_line(size = .7, color = "black"),
    panel.border = element_blank())

# Note transparent background for the second plot
p2 <- 
  ggplot(data=df2) +
  geom_line(linetype="dashed",size=0.5,aes(x=month,y=temp,group=1)) +
  scale_y_continuous(name = "Water temperature (°C)", limits = c(20,32)) +
  scale_x_discrete(limits=c("Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec")) +
  theme_bw(base_size = 12, base_family = "Helvetica") + 
  theme(panel.grid = element_blank()) +
  theme( # Increase size of axis lines
    axis.line.x = element_line(size = .7, color = "black"),
    axis.line.y = element_line(size = .7, color = "black"),
    panel.border = element_blank(),
    panel.background = element_rect(fill = "transparent"))

# Get the ggplot grobs
g1 <- ggplotGrob(p1)
g2 <- ggplotGrob(p2)


# Get the location of the plot panel in g1.
# These are used later when transformed elements of g2 are put back into g1
pp <- c(subset(g1$layout, name == "panel", se = t:r))

# Overlap panel for second plot on that of the first plot
g1 <- gtable_add_grob(g1, g2$grobs[[which(g2$layout$name == "panel")]], pp$t, pp$l, pp$b, pp$l)

# Then proceed as before:

# ggplot contains many labels that are themselves complex grob; 
# usually a text grob surrounded by margins.
# When moving the grobs from, say, the left to the right of a plot,
# Make sure the margins and the justifications are swapped around.
# The function below does the swapping.
# Taken from the cowplot package:
# https://github.com/wilkelab/cowplot/blob/master/R/switch_axis.R 

hinvert_title_grob <- function(grob){

  # Swap the widths
  widths <- grob$widths
  grob$widths[1] <- widths[3]
  grob$widths[3] <- widths[1]
  grob$vp[[1]]$layout$widths[1] <- widths[3]
  grob$vp[[1]]$layout$widths[3] <- widths[1]

  # Fix the justification
  grob$children[[1]]$hjust <- 1 - grob$children[[1]]$hjust 
  grob$children[[1]]$vjust <- 1 - grob$children[[1]]$vjust 
  grob$children[[1]]$x <- unit(1, "npc") - grob$children[[1]]$x
  grob
}

# Get the y axis title from g2
index <- which(g2$layout$name == "ylab-l") # Which grob contains the y axis title?
ylab <- g2$grobs[[index]]                # Extract that grob
ylab <- hinvert_title_grob(ylab)         # Swap margins and fix justifications

# Put the transformed label on the right side of g1
g1 <- gtable_add_cols(g1, g2$widths[g2$layout[index, ]$l], pp$r)
g1 <- gtable_add_grob(g1, ylab, pp$t, pp$r + 1, pp$b, pp$r + 1, clip = "off", name = "ylab-r")

# Get the y axis from g2 (axis line, tick marks, and tick mark labels)
index <- which(g2$layout$name == "axis-l")  # Which grob
yaxis <- g2$grobs[[index]]                  # Extract the grob

# yaxis is a complex of grobs containing the axis line, the tick marks, and the tick mark labels.
# The relevant grobs are contained in axis$children:
#   axis$children[[1]] contains the axis line;
#   axis$children[[2]] contains the tick marks and tick mark labels.

# First, move the axis line to the left
yaxis$children[[1]]$x <- unit.c(unit(0, "npc"), unit(0, "npc"))

# Second, swap tick marks and tick mark labels
ticks <- yaxis$children[[2]]
ticks$widths <- rev(ticks$widths)
ticks$grobs <- rev(ticks$grobs)

# Third, move the tick marks
ticks$grobs[[1]]$x <- ticks$grobs[[1]]$x - unit(1, "npc") + unit(3, "pt")

# Fourth, swap margins and fix justifications for the tick mark labels
ticks$grobs[[2]] <- hinvert_title_grob(ticks$grobs[[2]])

# Fifth, put ticks back into yaxis
yaxis$children[[2]] <- ticks

# Put the transformed yaxis on the right side of g1
g1 <- gtable_add_cols(g1, g2$widths[g2$layout[index, ]$l], pp$r)
g1 <- gtable_add_grob(g1, yaxis, pp$t, pp$r + 1, pp$b, pp$r + 1, clip = "off", name = "axis-r")

# Draw it
grid.newpage()
grid.draw(g1)