Print data.frame column and color by type

Question

In my knitted document, I am trying to print a data column. To help the visualization, I would like to change the color of the output to change depending on the value of another column. I have a simple example as follows.

date_vector <- rep(NA, 10)
type_vector <- rep(NA, 10)
types <- c("A", "B")
CDate <- Sys.Date()
date_vector[1] <- as.character(CDate)
type_vector[1] <- sample(types, size = 1)
for (i in 2:10) {
  CDate <- as.Date(CDate) + rexp(n = 1, rate = 1/5)
  date_vector[i] <- as.character(CDate)
  type_vector[i] <- sample(types, size = 1)
}

test_df <- data.frame(Date=date_vector, Type=type_vector)

When I print test_df$Date, I see the following

date_vector
[1] "2016-01-06" "2016-01-07" "2016-01-22" "2016-01-28" "2016-01-29" "2016-02-01" "2016-02-04"
[8] "2016-02-12" "2016-02-13" "2016-02-15"

Instead, I would like to see the following

Since the type of records was as follows

type_vector
[1] "A" "A" "B" "B" "A" "A" "B" "A" "B" "A"

So blue represents dates with a type A, and green represents dates with a type B.

Answer 1

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printHighlighted <- function(x, condition = rep(FALSE, length(x)), highlight = "\\emph{%s}", printIndex = TRUE, width = getOption("width"), digits = getOption("digits"), quote = NULL) {

  stopifnot(length(x) == length(condition))
  stopifnot(missing(digits) || (!missing(digits) && is.numeric(x))) # Raise error when input is non-numeric but "digits" supplied.

  if (missing(quote)) {
    if (is.numeric(x) || is.logical(x)) {
      quote <- FALSE
    } else {
      quote <- TRUE
    }
  }

  nquotes <- 0

  if (!printIndex) {
    currentLineIndex <- ""
  }

  if (is.numeric(x)) {
    x <- round(x, digits = digits)
  }

  fitsInLine <- function(x, elementsCurrentLine, currentLineIndex, nquotes, width) {
    return(sum(nchar(x[elementsCurrentLine])) + # total width of elements in current line
             nchar(currentLineIndex) + # width of the index of the first element (if shown)
             sum(elementsCurrentLine) - 1 + # width of spaces between elements
             nquotes <= # width of quotes added around elements
             width)
  }

  x <- as.character(x)
  elementsCurrentLine <- rep(FALSE, times = length(x))


  for (i in seq_along(x)) {

    if (!any(elementsCurrentLine) && printIndex) { # this is a new line AND show index
      currentLineIndex <- sprintf("[%s] ", i)
    }

    elementsCurrentLine[i] <- TRUE # Add element i to current line. Each line holds at least one element. Therefore, if i is the first element of this line, add it regardless of line width. If there already are elements in the line, the previous loop iteration checked that this element will fit.

    if (i < length(x)) { # not the last element

      # check whether next element will fit in this line
      elementsCurrentLineTest <- elementsCurrentLine
      elementsCurrentLineTest[i + 1] <- TRUE

      if (quote) {
        nquotes <- sum(elementsCurrentLineTest) * 2
      }

      if (fitsInLine(x, elementsCurrentLineTest, currentLineIndex, nquotes, width)) {
        next # Next element will fit; do not print yet.
      }
    }

    # Next element won't fit in current line. Print and start a new line.

    # print
    toPrint <- x[elementsCurrentLine]
    toMarkup <- condition[elementsCurrentLine]

    toPrint[toMarkup] <- sprintf(fmt = highlight, toPrint[toMarkup]) # add highlighting

    if (quote) {
      toPrint <- sprintf('"%s"', toPrint)
    }

    cat(currentLineIndex)
    cat(toPrint)
    cat("\n")

    # clear line
    elementsCurrentLine <- rep(FALSE, times = length(x))
  }
}

knitr, chunk results = "asis", verbatim, , .

, ,

\begin{knitrout}
\definecolor{shadecolor}{rgb}{0.969, 0.969, 0.969}\color{fgcolor}
\begin{kframe}
\begin{alltt}
<<your-chunk>>=
printHighlighted(...)
@
\end{alltt}
\end{kframe}
\end{knitrout}

, , printHighlighted printHighlighted.R.

\documentclass{article}
\begin{document}

Some text ....

\begin{knitrout}\definecolor{shadecolor}{rgb}{0.969, 0.969, 0.969}\color{fgcolor}\begin{kframe}\begin{alltt}
<<results = "asis", echo = FALSE>>=
source("printHighlighted.R")
data <- seq(from = as.Date("2015-01-15"), by = "day", length.out = 100)
cond <- rep(FALSE, 100)
cond[c(3, 55)] <- TRUE

printHighlighted(x = data, condition = cond, highlight = "\\textcolor{blue}{%s}", width = 60)
@
\end{alltt}\end{kframe}\end{knitrout}

Some text ....

\end{document}

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