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mathematicalcoffee/autocaption_knitr.r

Created April 23, 2013 07:12
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Automatically set knitr's figure caption option to the title of the ggplot in the chunk. The gist has the R code you should put in your document, as well as an example Rmd with the compiled output.
Raw
autocaption_knitr.r
# Include the following in a chunk up the top of your document
# Then in your plot chunk, use 'fig.cap=cap()'.
# Set the title of your ggplot via `labs(title="mytitle")`, and
# it will automatically be substituted into the chunk options
# as 'fig.cap'
library(knitr)
opts_knit$set(eval.after='fig.cap')
cap <- function () {
p <- last_plot()
if (!is.null(p) && !is.null(p$labels$title)) {
paste('Figure:', p$labels$title)
} else {
NULL # null caption
}
}
Raw
example.html
<!DOCTYPE html>
<!-- saved from url=(0014)about:internet -->
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<title>Example of using the autocaption script.</title>
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color:#666666;
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}
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max-width:100%;
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text-decoration: underline;
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}
pre, blockquote {
padding-right: 1em;
page-break-inside: avoid;
}
tr, img {
page-break-inside: avoid;
}
img {
max-width: 100% !important;
}
@page :left {
margin: 15mm 20mm 15mm 10mm;
}
@page :right {
margin: 15mm 10mm 15mm 20mm;
}
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pre .operator,
pre .paren {
color: rgb(104, 118, 135)
}
pre .literal {
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}
pre .number {
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}
pre .comment {
color: rgb(76, 136, 107);
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<h1>Example of using the autocaption script.</h1>
<p>In this document, I create plots with <code>ggplot2</code> and give them titles using <code>labs(title=&quot;...&quot;)</code>.
The autocaption script enables me to set <code>fig.cap=cap()</code> in my chunk options, and the <code>fig.cap</code> option will <em>automatically</em> be set to the title of the ggplot.</p>
<p>Compile it using:</p>
<pre><code class="r">library(knitr)
knit2html(&quot;example.Rmd&quot;)
</code></pre>
<h2>Step 1: include the script</h2>
<p>Include the following chunk in your document.
I recommend setting <code>echo=F</code> so it is hidden, and place it up the top of your document somewhere (before any of your actual chunks).</p>
<pre><code class="r"># This sets up the autocaption script
library(knitr)
opts_knit$set(eval.after = &quot;fig.cap&quot;)
cap &lt;- function() {
p &lt;- last_plot()
if (!is.null(p) &amp;&amp; !is.null(p$labels$title)) {
paste(&quot;Figure:&quot;, p$labels$title)
} else {
NULL # null caption
}
}
</code></pre>
<h2>Step 2: do some plots</h2>
<p>To do some plots you plot as you usually would, except that you put <code>fig.cap=cap()</code> into the chunk options.
For example, the following chunk (without the space between the &#39;{&#39; and the &#39;r&#39;):</p>
<pre><code>```{ r fig.cap=cap()}
library(ggplot2)
ggplot(iris, aes(x=Sepal.Length, y=Petal.Length, colour=Species)) +
geom_point() +
labs(title=&#39;Petal length vs Sepal length&#39;)
```
</code></pre>
<p>produces:</p>
<pre><code class="r">library(ggplot2)
ggplot(iris, aes(x = Sepal.Length, y = Petal.Length, colour = Species)) + geom_point() +
labs(title = &quot;Petal length vs Sepal length&quot;)
</code></pre>
<p><img src="data:image/png;base64,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" alt="Figure: Petal length vs Sepal length"/> </p>
<p>Note that the plot title and figure caption are in sync, and I only had to specify the title in one place (on the plot).
Note - in HTML the alt text is the &ldquo;figure caption&rdquo; (unless you use Pandoc to compile the md to HTML); in LaTeX the caption shows up as a figure caption.
This is the same as if I&#39;d done (without the space between the &#39;{&#39; and the &#39;r&#39;):</p>
<pre><code>```{ r fig.cap=&#39;Petal length vs Sepal length&#39;}
library(ggplot2)
ggplot(iris, aes(x=Sepal.Length, y=Petal.Length, colour=Species)) +
geom_point() +
labs(title=&#39;Petal length vs Sepal length&#39;)
```
</code></pre>
<p>but prevents me from having to type the same title twice.</p>
<h2>Caveats</h2>
<p>There are restrictions on its use:</p>
<ul>
<li>Only works with <code>ggplot2</code> plots, not (say) base graphics</li>
<li>If you have multiple plots in a chunk, they will <em>all</em> get the caption of the last plot of the chunk, so you should only have one plot per chunk.</li>
</ul>
<h2>Conclusion</h2>
<p>Hope you liked it!</p>
</body>
</html>
Raw
example.Rmd
# Example of using the autocaption script.
In this document, I create plots with `ggplot2` and give them titles using `labs(title="...")`.
The autocaption script enables me to set `fig.cap=cap()` in my chunk options, and the `fig.cap` option will *automatically* be set to the title of the ggplot.
Compile it using:
```{r eval=F}
library(knitr)
knit2html('example.Rmd')
```
## Step 1: include the script
Include the following chunk in your document.
I recommend setting `echo=F` so it is hidden, and place it up the top of your document somewhere (before any of your actual chunks).
```{r autocaption, echo=T}
# This sets up the autocaption script
library(knitr)
opts_knit$set(eval.after='fig.cap')
cap <- function () {
p <- last_plot()
if (!is.null(p) && !is.null(p$labels$title)) {
paste('Figure:', p$labels$title)
} else {
NULL # null caption
}
}
```
## Step 2: do some plots
To do some plots you plot as you usually would, except that you put `fig.cap=cap()` into the chunk options.
For example, the following chunk (without the space between the '{' and the 'r'):
```{ r fig.cap=cap()}
library(ggplot2)
ggplot(iris, aes(x=Sepal.Length, y=Petal.Length, colour=Species)) +
geom_point() +
labs(title='Petal length vs Sepal length')
```
produces:
```{r fig.cap=cap()}
library(ggplot2)
ggplot(iris, aes(x=Sepal.Length, y=Petal.Length, colour=Species)) +
geom_point() +
labs(title='Petal length vs Sepal length')
```
Note that the plot title and figure caption are in sync, and I only had to specify the title in one place (on the plot).
Note - in HTML the alt text is the "figure caption" (unless you use Pandoc to compile the md to HTML); in LaTeX the caption shows up as a figure caption.
This is the same as if I'd done (without the space between the '{' and the 'r'):
```{ r fig.cap='Petal length vs Sepal length'}
library(ggplot2)
ggplot(iris, aes(x=Sepal.Length, y=Petal.Length, colour=Species)) +
geom_point() +
labs(title='Petal length vs Sepal length')
```
but prevents me from having to type the same title twice.
## Caveats
There are restrictions on its use:
* Only works with `ggplot2` plots, not (say) base graphics
* If you have multiple plots in a chunk, they will *all* get the caption of the last plot of the chunk, so you should only have one plot per chunk.
## Conclusion
Hope you liked it!
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