我正在尝试增加第二个轴标题作为grob的字体大小（出于显而易见的原因）。这是一些要绘制图形的玩具数据

library(Hmisc)
library(dplyr)

# Plot power vs. n for various odds ratios 
(n  <- seq(10,1000,by=10)) # candidate sample sizes
(OR <- as.numeric(sort(c(seq(1/0.90,1/0.13,length.out = 9),2.9)))) # candidate odds ratios,spanning the 95% CI centered around what we got (OR=2.9)
alpha <- c(.001,.01,.05)

# put all of these into a dataset and calculate power
powerDF <- data.frame(expand.grid(OR,n,alpha)) %>% 
           rename(OR = Var1,num = Var2,alph = Var3) %>%
           arrange(OR) %>%
           mutate(power = as.numeric(bpower(p1=.29,odds.ratio=OR,n=num,alpha = alph))) %>%
           transform(OR = factor(format(round(OR,2),nsmall=2)),alph = factor(ifelse(alph == 0.001,"p=0.001",ifelse(alph == 0.01,"p=0.01","p=0.05"))))

Now for the figure

library(grid)
library(gtable)

p2 <- ggplot(powerDF,aes(x = num,y = power,colour = factor(OR))) + 
             geom_line() +
             facet_grid(factor(alph)~.) +
             labs(x = "sample size") +
             scale_colour_discrete(name = "Odds Ratio") +
             scale_x_continuous(breaks = seq(0,100)) +
             scale_y_continuous(breaks = seq(0,1,.1)) + 
             theme_light() +
             theme(axis.title.x = element_text(size = 12,face = "bold"),axis.title.y = element_text(size = 12,axis.text = element_text(size = 11),panel.grid.minor = element_blank(),panel.grid.major.y = element_line(colour = "gray95"),panel.grid.major.x = element_line(colour = "gray95"),strip.text = element_text(colour = 'black',face = 'bold',size = 12),legend.text = element_text(size = 12),legend.title = element_text(size = 12,face = "bold")) 
p2

现在将第二个轴标题添加为grob。

g <- ggplotGrob(p2)
rect <- grobTree(rectGrob(gp = gpar(fill = "white",col = "white")),textGrob(expression(bold("Significance Level")),rot = -90,gp = gpar(col = "black")))
g <- gtable_add_cols(x = g,widths = g$widths[6],pos = 6) # add a column g$widths[6] wide to the right of horizontal position 6
g <- gtable_add_grob(x = g,grobs = rect,l=7,t=7,b=11) # now add the rect grob at the new column position to the right of position 6 (i.e. left-most position y,or l= 7,spanning the whole graph)
grid.newpage()
grid.draw(g)

一切都很好。但是如何在textGrob()内增加第二个轴的字体大小？

我尝试fontsize =，cex =，face =无济于事，并且textGrob()文档未提及字体大小。