Dear R-help

I am using Knitr and ggplot to draft an article and have now started to
improve on the layout and graphics. So far I have not been able to maintain
the same font size for labels in all my figures.

My goal is to be able to change the width of the figures while maintaining
the same font. This works for the height parameter (example not included).

In the true document I also use tikz, but the problem can be reproduced
without it.

I know the question is very specific, but my understanding is that this
combination of packages  is common. (They are really great. Keep up the
good work.)  There has to be others facing the same problem and someone
must have found a nice solution.

Additional attempts from my side which failed are not included in the
example. I have tested the Google results i could find without any luck.

Cheers
Daniel

PS. I know the example plots could have been smaller, but they just became
too ugly for me


\documentclass{article}
\begin{document}

<<setup, include=FALSE, cache=FALSE>>=
library(knitr)
library(ggplot2)
@

\title{Knitr and ggplot2}
\author{Daniel Haugstvedt}

\maketitle

There are four plots in this article. Figure \ref{fig:plot-figHeight} uses
the argument fig.height=2.5 while Figures \ref{fig:plot-figWidth}
used both fig.height=2.5 and fig.width=3. The later option makes the font
too big.

An alternative approach is used in Figures  \ref{fig:plot-figOutWidthBig}
and
 \ref{fig:plot-figOutWidthSmall}. There the argument out.width is set to
 12 and 8 cm respectively. This stops the problem of excessively large fonts
 for figures with smaller width, but there is still no consistency
 across plots in terms of font size.

<<plot-figHeight, echo=FALSE, fig.height=2.5, fig.cap="Density plot with no
fig.width argument", fig.pos='ht'>>=
df = data.frame(x = rnorm(100), y = 1:100)
ggplot(df, aes(x = x)) +
  geom_histogram(aes(y = ..density..),
                 binwidth = 1, colour = "black", fill = "white") +
  xlab("Improvement, %") +
  ylab("Density") +
  theme_classic()
@

<<plot-figWidth, echo=FALSE, fig.height=2.5, fig.width = 3,
fig.cap="Density plot with fig.width=3", fig.pos='ht'>>=
ggplot(df, aes(x = x)) +
  geom_histogram(aes(y = ..density..),
                 binwidth = 1, colour = "black", fill = "white") +
  xlab("Improvement, %") +
  ylab("Density") +
  theme_classic()
@

<<plot-figOutWidthBig, echo=FALSE, fig.height=2.5, out.width = "12cm",
fig.cap="Density plot with out.width=12cm", fig.pos='ht'>>=
ggplot(df, aes(x = x)) +
  geom_histogram(aes(y = ..density..),
                 binwidth = 1, colour = "black", fill = "white") +
  xlab("Improvement, %") +
  ylab("Density") +
  theme_classic()
@

<<plot-figOutWidthSmall, echo=FALSE, fig.height=2.5, out.width = "8cm",
fig.cap="Density plot with out.width=8cm", fig.pos='ht'>>=
ggplot(df, aes(x = x)) +
  geom_histogram(aes(y = ..density..),
                 binwidth = 1, colour = "black", fill = "white") +
  xlab("Improvement, %") +
  ylab("Density") +
  theme_classic()
@

\end{document}

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