将两个命令添加到 xtable 中的 add.to.row 参数

Question

我已使用下面的两个答案为 xtable 中的交替行添加颜色或为长表添加页脚，但我需要弄清楚如何做到这两点。

(1)How to only show table caption once in "list of table" for a table split onto multiple pages 和

(2) R, knitr, xtable, alternating row colors

有没有办法同时使用两者？

Answer 1

从您列出的答案看来，您使用 LaTeX 作为输出。您可以通过为每个命令分配一个位置来组合两个或多个 add.to.row 命令。命令必须是模式character 的向量，并且位置必须在列表中。在下文中，我创建一个列表addtorow <- list()，然后分配位置：addtorow$pos <- as.list(c(rowIndexForFirstCommands, rowIndexForSecondCommands)) 及其对应的命令到addtorow$command <- as.vector(c(firstCommands, secondCommands),mode="character")。这是一个最小的工作示例：

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[english]{babel}
\usepackage{longtable}
\usepackage[table]{xcolor}
\begin{document}

<<yoman,echo=FALSE,results='asis'>>=
library(xtable)
#define a data frame
mydf <- data.frame(id = make.unique(rep(letters, length.out = 100), sep=''), 
                   var1 = rnorm(100), 
                   var2 = runif(100),
                   var3=rexp(100),
                   var4=rpois(100,1.4))

#define row indexes to be highlighted (each two), 
#and repeat rowcolor command correspondingly
rws <- seq(1, (nrow(mydf)), by = 2)
col <- rep("\\rowcolor[gray]{0.95}", length(rws))

#create a list that will receive the instructions 
#for add.to.row and add the two instructions
addtorow <- list()

#assign a position argument to addtorow
#rws are the row indexes for the row to be colored, 
#0 is the row index for longtable argument
addtorow$pos <- as.list(c(
                         rws, #positions for first commands(highlighting rows)
                         0    #position for second command (longtable argument)
                         ))

#assign corresponding commands to addtorow
addtorow$command <- as.vector(c( col, #first command (highlighting rows)
                                 paste("\\hline \n",
                                       "\\endhead \n",
                                       "\\hline \n",
                                       "{\\footnotesize Continued on next page} \n",
                                       "\\endfoot \n",
                                       "\\endlastfoot \n",
                                       sep="")), #second command (longtable)
                              mode="character")
print(xtable(mydf,
             caption = "My caption "),
             tabular.environment = "longtable",
             floating = FALSE,
             include.colnames = TRUE,
             include.rownames = TRUE, 
             add.to.row = addtorow,    
             hline.after=c(-1),        # addtorow substitute default hline for first row
             caption.placement="top")

@

\end{document}