在R的ggplot中使用稻穗Unicode字符(U+1F33E)时出现无效序列错误

问题说明 #

尝试用ggplot绘制包含稻穗字符🌾（U+1F33E）的图形时，使用转义序列"\u{1f33e}"会触发错误：Error: invalid \u{xxxx} sequence。但使用4位Unicode字符（如U+2620）的代码可正常运行，且已确认所用的Arial Unicode MS字体包含该稻穗字符。

可正常运行的示例代码（U+2620） #

library(ggplot2)
df <- read.table(text="x y
                 1    3 
                 2    4 
                 3    6 
                 4    7 ", header=TRUE) 
ggplot(data = df, aes(x, y)) +  
  geom_text(label="\u2620", size = 10, family = "Arial Unicode MS") 

报错的稻穗字符代码 #

ggplot(data = df, aes(x, y)) +  
  geom_text(label="\u{1f33e}", size = 10, family = "Arial Unicode MS")

错误信息：

Error: invalid \u{xxxx} sequence (line 2)

R会话信息 #

> sessionInfo()
R version 4.0.2 (2020-06-22)
Platform: x86_64-apple-darwin17.0 (64-bit)
Running under: OS X  12.5.1

Matrix products: default
LAPACK: /Library/Frameworks/R.framework/Versions/4.0/Resources/lib/libRlapack.dylib

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

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

other attached packages:
[1] ggplot2_3.3.2

loaded via a namespace (and not attached):
 [1] magrittr_2.0.3   tidyselect_1.1.2 munsell_0.5.0    colorspace_2.0-2
 [5] R6_2.5.1         rlang_1.0.2      fansi_1.0.3      blob_1.2.1      
 [9] dplyr_1.0.8      tools_4.0.2      grid_4.0.2       gtable_0.3.0    
[13] utf8_1.2.2       cli_3.3.0        DBI_1.1.0        withr_2.5.0     
[17] ellipsis_0.3.2   digest_0.6.29    assertthat_0.2.1 tibble_3.1.6    
[21] lifecycle_1.0.1  farver_2.0.3     purrr_0.3.4      vctrs_0.4.1     
[25] glue_1.6.2       labeling_0.3     compiler_4.0.2   pillar_1.8.1    
[29] generics_0.1.3   scales_1.1.1     pkgconfig_2.0.3 

> capabilities()
       jpeg         png        tiff       tcltk         X11        aqua    http/ftp 
       TRUE        TRUE        TRUE        TRUE        TRUE        TRUE        TRUE 
    sockets      libxml        fifo      cledit       iconv         NLS     profmem 
       TRUE        TRUE        TRUE        TRUE        TRUE        TRUE        TRUE 
      cairo         ICU long.double     libcurl 
       TRUE        TRUE        TRUE        TRUE 

解决方法 #

• 直接粘贴字符：跳过转义序列，直接把稻穗字符🌾粘贴到label参数中：

  ggplot(data = df, aes(x, y)) +  
    geom_text(label="🌾", size = 10, family = "Arial Unicode MS")
  

• 使用intToUtf8()生成字符：通过Unicode码点直接生成目标字符，避免转义错误：

  ggplot(data = df, aes(x, y)) +  
    geom_text(label=intToUtf8(0x1F33E), size = 10, family = "Arial Unicode MS")
  

• 更新R版本：你的R版本4.0.2对8位Unicode转义序列（\u{xxxxxx}）的支持不完善，更新到R 4.1及以上版本后，"\u{1f33e}"的写法即可正常使用。

内容的提问来源于stack exchange，提问作者Gopal Penny