R xtable with multipleolumns and booktabs

Question

我想將data.frame轉換爲帶有多列的（booktab）乳膠表，但是我無法創建將\toprule置於表之上的輸出。下面的數據是用來

dat <- structure(c(841.8, 804.4, 135.1, 106.2, 0.7025, 0.09645, 305.2, 
707.1, 449.3, 119.9, 0.7025, 0.09645), .Dim = c(2L, 6L), .Dimnames = list(
c("ev", "smooth"), c("Mean", "SD", "best", "Mean", "SD", 
"best"))) 

> dat  
    Mean SD best Mean SD best 
    ev  841.8 135.1 0.70250 305.2 449.3 0.70250 
    smooth 804.4 106.2 0.09645 707.1 119.9 0.09645 

addtorow <- list() 
addtorow$pos <- list(-1) 
addtorow$command <- '& \\multicolumn{3}{c}{Tab a}& \\multicolumn{3}{c}{Tab b}\\\\' 

print(xtable(dat), add.to.row=addtorow, include.colnames=TRUE,booktabs=TRUE) 

輸出看起來幾乎是正確的，但\toprule是在錯誤的位置。

\begin{table}[ht] 
\centering 
\begin{tabular}{rrrrrrr} 
    & \multicolumn{3}{c}{In-sample}& \multicolumn{3}{c}{Out-of-sample}\\  
    \toprule 
    & Mean & SD & best & Mean & SD & best \\ 
    \midrule 
    ev & 841.80 & 135.10 & 0.70 & 305.20 & 449.30 & 0.70 \\ 
    smooth & 804.40 & 106.20 & 0.10 & 707.10 & 119.90 & 0.10 \\ 
    \bottomrule 
\end{tabular} 
\end{table} 

更改addtorow$pos<-list(0)是不是一個答案，因爲它正確地放置在頂部規則，但把下表的列名的多列行。我正在尋找以下輸出：

\begin{table}[ht] 
\centering 
\begin{tabular}{rrrrrrr} 
\toprule 
& \multicolumn{3}{c}{In-sample}& \multicolumn{3}{c}{Out-of-sample}\\ 
& Mean & SD & best & Mean & SD & best \\ 
\midrule 
ev & 841.80 & 135.10 & 0.70 & 305.20 & 449.30 & 0.70 \\ 
smooth & 804.40 & 106.20 & 0.10 & 707.10 & 119.90 & 0.10 \\ 
\bottomrule 
\end{tabular} 
\end{table} 

非常感謝您的任何意見。

Answer 1

我強烈建議使用驚人的kableExtra package。

\documentclass{article} 
\usepackage{booktabs} 
\begin{document} 

<<setup, include=FALSE>>= 
library(knitr) 
opts_chunk$set(echo=FALSE) 
library(kableExtra) 
options(knitr.table.format = "latex") 
dat <- structure(c(841.8, 804.4, 135.1, 106.2, 0.7025, 0.09645, 305.2, 
707.1, 449.3, 119.9, 0.7025, 0.09645), .Dim = c(2L, 6L), .Dimnames = list(
c("ev", "smooth"), c("Mean", "SD", "best", "Mean", "SD", 
"best"))) 
@ 

<<results='asis'>>= 
kable(dat, booktabs = TRUE, caption = "My table", align = "c") %>% 
    add_header_above(c(" ", "Tab a"=3, "Tab b"=3)) %>% 
    kable_styling(latex_options = "hold_position") 
@ 

\end{document}