° symbol and other unicode codes in knitr

To use ° symbol in knitr or sweave, first load the latex package gensymb  and after use this code $\degree$.

Then the beginning of your code should be something like that:

\documentclass[a4paper]{article}

\usepackage{gensymb}

If the package gensymb is not present, alternative is to do:

\documentclass[a4paper]{article}

\DeclareTextSymbol{\degree}{OT1}{23}

###############################################

To use the ° symbol within a chunk, you must define the encoding. Be sure also to save the .Rnw file using the same encoding (command File -> Save with encoding... in Rstudio).

For latin1:

\documentclass[a4paper]{article}

\usepackage[latin1]{inputenc}

\begin{document}

<<>>=

degree <- "°"

print(degree)

@

\end{document}

For utf8 (based on a remark of  Yihui Xie in r-help list):

If you use pdflatex, you have to declare the font encoding

\usepackage[T1]{fontenc} when you save the document with UTF-8:

\documentclass{article}

\usepackage[T1]{fontenc}

\usepackage[utf8]{inputenc}

\begin{document}

<<>>=

degree <- "°"

print(degree)

@

\end{document}

For XeTeX, you will have to use different packages, fontspec and

xunicode. Here is a minimal example for XeTeX:

\documentclass{article}

\usepackage{fontspec}

\usepackage{xunicode}

\begin{document}

<<>>=

degree <- "°"

print(degree)

@

\end{document}