Creating a tikz picture with 2 plots in a row

Question

I've got a question concerning the creation of two plots in a row, using R with Package tikz device to send the tikz to Latex. What I want to do is, plotting 2 graphs in a row. What I did first was to create to plots in the par(mfrow=c(1,2)) ambiance. But this doesn't work good, because the Plots are like vertical rectangles, when printing with Latex. What I want to have is to get two pictures in a row which are quadratic. So what I did next, I created a layout:

Layout<- matrix(c(1, 2), nrow = 1, ncol=2, byrow = TRUE)
nf <- layout(mat = Layout, widths = c(1,1),heights = c(1,1), respect = TRUE)
layout.show(nf)

and plotted the two graphs. The result is quadratic (that's good), but when I add a caption to the two plots (in Latex) it is far out from the graph. What am I suppose to do? Any thougts are appreciated!

Answer 1

You specified respect=TRUE, so that means that your plots within the device only take up half of the height (if using defaults on the tikz device) and the rest of the height is filled with whitespace. When you add a caption it is offset from the plots by that whitespace. When you open the tikz device set the height and the width so that the height is close to half the width and you should end up with a lot less whitespace in the end and the caption will be closer to the plots.

Answer 2

As Greg mentioned, you have to adjust the width and the height of the plot canvas if you want square plots but don't want R to fill in large borders of whitespace.

Here is a minimal example using Sweave:

\documentclass{article}
\usepackage{Sweave}
\usepackage{tikz}
<<echo=FALSE,results=hide>>=
  require(tikzDevice)
@

\begin{document}

\begin{figure}
<<echo=FALSE,results=hide>>=
  # Standard LaTeX article class has a \textwidth of ~4.5in
  # Therefore, divide by 2 to get the right height.
  tikz('layout-ex.tex', width = 4.5, height = 2.25)

  Layout<- matrix(c(1, 2), nrow = 1, ncol=2, byrow = TRUE)
  nf <- layout(mat = Layout, widths = c(1,1),heights = c(1,1), respect = TRUE)
  layout.show(nf)

  dev.off()
@

  \centering
  \input{layout-ex}
  \label{fig:layout-ex}
  \caption{A layout with two sub-figures}
\end{figure}

\end{document}

The resulting figure looks like this: