Add a Caption and Label
# Load packages from the local library into the R session.
library(rattle) # For the weatherAUS dataset.
library(ggplot2) # To generate a density plot.
# Identify cities of interest.
<- c("Canberra", "Darwin", "Melbourne", "Sydney")
# Generate the plot.
weatherAUS subset(Location %in% cities & ! is.na(Temp3pm)) %>%
ggplot(aes(x=Temp3pm, colour=Location, fill=Location)) +
Adding a caption (which automatically also adds a label) is done using
<<myfigure, fig.cap="The 3pm temperature for four locations.", fig.pos="h",...}
... R code ...
We have also used (but can’t see) fig.pos=
requests placement of the figure `
here'' rather than letting it float. Other options are to place the figure at the top of a page (“t”
), or the bottom of a page (“b”`). We can leave it
empty and the placement is done automatically—that is, the figure
floats to an appropriate location.
Once a caption is added, a label is also added to the figure so that
it can be referred to in the document. The label is made up of
fig: followed by the chunk label, which is
this example. So we can refer to the figure using
allows us to refer to Figure @ref(fig:knitr:myfigure_3pm_temp) on