kableExtra生成LaTeX/PDF表格时多行通用脚注的显示异常问题

异常根因 #

• 脚注区域输出makecell[1]乱码：该问题和字符转义无关，是kableExtra的参数兼容bug。当同时开启threeparttable = T和footnote_as_chunk = T时，函数会错误触发makecell对象的序列化渲染分支，本该被LaTeX宏解析的内部索引值会被当成普通文本输出，因此调整escape参数无法消除该异常。
• 脚注宽度不与表格匹配：未开启表格专属脚注环境时，脚注会以页面文本宽度排版，不会自动对齐表格总宽度，长文本无法自动折行适配表格尺寸。

修正后可直接运行的代码 #

# 构造示例数据
ID <- c(paste("G0", as.character(1:9), sep = ""),"G10","G11","Mean")
V1 <- c(10.06,11.06,12.06,13.06,14.06,15.06,16.06,17.07,18.07,19.07,6.88,13.86)
V2 <- c(0.21,0.03,0.09,0.03,0.09,0.03,0.09,0.03,0.09,0.21,0.31,NA)
tbl <- data.frame(ID, V1, V1, V2, V1, V2, V1, V2, V2)
colnames(tbl) <- c('ID','Get. \\%','Get. \\%','K','Get. \\%','K','Get. \\%','K','P')

# 全局配置
options(knitr.kable.NA = '--')
library(kableExtra)

# 生成适配PDF输出的表格
kbl(tbl, format = 'latex', align = 'l', booktabs = T, escape = F, digits = 2,
    linesep = "", caption = "This is a table caption.", threeparttable = T) %>%
  add_header_above(c(" ", "AB", "BP" = 2, "CK" = 2, "JAM" = 2, ""), bold = T) %>%
  column_spec(1, width = '1.15cm') %>%
  row_spec(11, hline_after = T) %>%
  row_spec(12, bold = T) %>%
  kable_styling(position = "center", latex_options = "hold_position") %>%
  footnote(general_title = "Note.", footnote_as_chunk = F, escape = F,
           general = "Relatively long footnote that I would like to span a couple of lines. Relatively long footnote that I would like to span a couple of lines.")

避坑说明 #

• 你之前验证的「通过kbl()设置threeparttable = T解决脚注不自动折行」的方案完全正确，只需要调整脚注参数避开兼容bug即可同时满足所有排版需求。
• 开启threeparttable = T后，禁止搭配footnote_as_chunk = T，这个组合在kableExtra当前稳定版本中可稳定复现makecell[1]的乱码问题。
• 之前反馈“footnote_as_chunk = F会导致脚注标题前多余换行”的问题，仅在未开启threeparttable时存在。开启threeparttable后，排版逻辑会切换为LaTeX原生表格脚注规则，脚注标题会默认和正文同排起始，不会出现多余换行。
• threeparttable环境会自动将脚注文本宽度约束为与表格总宽度一致，长文本自动跨多行排版，不需要手动在脚注字符串中插入换行符，也不需要额外设置脚注宽度参数。
• pdflatex、xelatex编译器默认内置threeparttable宏包，切换编译器不会对该排版效果产生影响。

内容的提问来源于stack exchange，提问作者Speleo4Life