r - ggplot scale_x_连续，符号为 : make bold

Question

问题是:我正在使用 ggplot 来制作一个 x 轴范围从 -90 到 90 度的图表。我已成功使用函数将度数符号添加到由scale_x_continuous创建的刻度标签中。但是，当我使用 theme() 调整字体时，刻度标签不会变为粗体。但是，更改字体大小是有效的。这是一个可重现的示例:

# function to add degree symbols
add_degree <- function(x) {
  parse(text = paste(x, "*degree",sep = ""))
}

y<- c(0.00552243346007605, 0.00553155893536122, 0.005693536121673, 
        0.0054722433460076, 0.00562661596958175, 0.00546768060836502, 
        0.00561292775665399, 0.00550950570342205, 0.0056851711026616, 
        0.00551558935361217, 0.0055041825095057, 0.00556501901140684, 
        0.00552699619771863, 0.00552623574144487, 0.0055680608365019, 
        0.00567148288973384, 0.00550342205323194, 0.00553764258555133, 
        0.00538098859315589, 0.00573307984790875, 0.00564486692015209, 
        0.00561444866920152, 0.00556349809885932, 0.00571254752851711, 
        0.00544030418250951, 0.00557946768060837, 0.00546083650190114, 
        0.00549049429657795, 0.00557414448669202, 0.00553916349809886, 
        0.00551787072243346, 0.00557794676806084, 0.0055041825095057, 
        0.00552699619771863, 0.0056509505703422, 0.00544790874524715, 
        0.00555555555555556)

x <- seq(-90,90,by = 5)
dat <- data.frame(x,y)
ggplot(dat,aes(x = x, y = y))+
  geom_line()+
  scale_x_continuous(limits = c(-90,90), breaks = seq(-90,90, by = 15), labels = add_degree)+
  theme_bw() +
  theme(

    # Adjust axis label and title font sizes below
    axis.title = element_text(size=12, face= "bold"),
    plot.title = element_text(size=12, face = "bold"),
    # Adjust size of tick labels
    axis.text.x = element_text(size=12, face = "bold"),
    axis.text.y = element_text(size=12, face = "bold"), 
    panel.grid.major = element_blank(),
    panel.grid.minor = element_blank(),
    panel.border = element_blank(),
    panel.background = element_blank(),
    axis.line = element_line(colour = "black")
  )

我尝试过调整上面的parse函数，但到目前为止还没有成功。我已经查看了以下解决方案，但无法使其在 ggplot 中工作:How to make beta italic and bold in axis label and P italic and bold in text

这是我的 sessionInfo() 输出:

R version 3.2.2 (2015-08-14)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 14.04.3 LTS

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C               LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8     LC_MONETARY=en_US.UTF-8   
 [6] LC_MESSAGES=en_US.UTF-8    LC_PAPER=en_US.UTF-8       LC_NAME=C                  LC_ADDRESS=C               LC_TELEPHONE=C            
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] reshape2_1.4.1 ggplot2_1.0.1  moments_0.14  

loaded via a namespace (and not attached):
 [1] Rcpp_0.12.0      digest_0.6.8     MASS_7.3-44      grid_3.2.2       plyr_1.8.3       gtable_0.1.2     magrittr_1.5     scales_0.2.5     stringi_0.5-5   
[10] proto_0.3-10     labeling_0.3     tools_3.2.2      stringr_1.0.0    munsell_0.4.2    colorspace_1.2-6

P.s.我相信这是一个与以下未回答的问题非常相似(如果不相同)的问题:making y-axis labels bold in ggplot (x-axis is set bold but y-axis label doesn't change) .

任何帮助将不胜感激!

Answer 1

我正在重用取自 similar question 的函数，只需要一点点调整。

make_labels <- function(value) {
  x <- as.character(value)
  do.call(expression, lapply(x, function(y) bquote(bold(.(y))^degree)))
}

现在，在您的 ggplot 调用中，使用 labels = make_labels 而不是 add_ Degree，您将得到