bold_example.Rnw

\documentclass{article}

\usepackage{hyperref}

\begin{document}

\section{Info}

Solution to \href{http://stackoverflow.com/questions/30309311/error-in-applying-a-for-loop-to-an-xtable-in-knitr}{this} Stack Overflow post. Tested with \texttt{xtable} version 1.7-4 on:

\begin{itemize}
\item{R version 3.2.0 (2015-04-16)}
\item{Platform: x86\_64-pc-linux-gnu (64-bit)}
\item{Running under: Ubuntu 14.04.2 LTS}
\end{itemize}

\section{Recreate \texttt{data.frame}}

<<>>=

library(xtable)

df.2 <- data.frame(
  DATE = c("2043:3","2043:4","2044:1","2044:2","2044:3","2044:4"),
  CY = c(rep(2043,2),rep(2044,4)),
  FY = c(rep(2044,4),rep(2045,2)),
  Quarter = c(3,4,1,2,3,4),
  XEMPNIN = c(3324.391,3326.214,3328.492,3330.100,3331.963,3334.248)
)


@

\section{Alter \texttt{bold()} function}

<<>>==
bold <- function(x, matrix) {
  
  x[] <- lapply(x, as.character)
  
  for (i in 1:ncol(x)) {   
    yes <- matrix[,i]
    x[yes,i] <- paste('\\textbf{', x[yes,i], '}', sep = "")  
  } 
  # change print() for return()
  return(x)
}

@

\section{Run OP code}

<<>>=

l.vec <- as.logical(c(1,1,1,1,1,
                      1,1,1,1,1,
                      0,0,0,0,0,
                      0,0,0,0,0,
                      0,0,0,0,0,
                      0,0,0,0,1))

l.mat <- matrix(l.vec, nrow = 6, ncol = 5, byrow = TRUE)

x.df.2 <- (xtable(df.2))

x.df.3 <- bold(x.df.2, l.mat)

@

\section{Print table}

Note \texttt{<<results="asis">>=} in chunk options:

<<results="asis">>=

print.xtable(
  x.df.3, 
  include.rownames = FALSE, 
  sanitize.text.function = identity
  )
@

\end{document}