Aesthetic specifications

library(ggplot2)
knitr::opts_chunk$set(fig.dpi = 96)

This vignette summarises the various formats that grid drawing functions take. Most of this information is available scattered throughout the R documentation. This appendix brings it all together in one place.

Colour

Colours can be specified with:

Line type {#sec:line-type-spec}

Line types can be specified with:

The size of a line is its width in mm.

Shape {#sec:shape-spec}

Shapes take four types of values:

Note that shapes 21-24 have both stroke colour and a fill. The size of the filled part is controlled by size, the size of the stroke is controlled by stroke. Each is measured in mm, and the total size of the point is the sum of the two. Note that the size is constant along the diagonal in the following figure.

sizes <- expand.grid(size = (0:3) * 2, stroke = (0:3) * 2)
ggplot(sizes, aes(size, stroke, size = size, stroke = stroke)) + 
  geom_abline(slope = -1, intercept = 6, colour = "white", size = 6) + 
  geom_point(shape = 21, fill = "red") +
  scale_size_identity()

Text

Font size

Font face

There are only three fonts that are guaranteed to work everywhere: "sans" (the default), "serif", or "mono":

df <- data.frame(x = 1, y = 3:1, family = c("sans", "serif", "mono"))
ggplot(df, aes(x, y)) + 
  geom_text(aes(label = family, family = family))

It's trickier to include a system font on a plot because text drawing is done differently by each graphics device (GD). There are five GDs in common use (png(), pdf(), on screen devices for Windows, Mac and Linux), so to have a font work everywhere you need to configure five devices in five different ways. Two packages simplify the quandary a bit:

Both approaches have pros and cons, so you will to need to try both of them and see which works best for your needs.

Family

Justification

Horizontal and vertical justification have the same parameterisation, either a string ("top", "middle", "bottom", "left", "center", "right") or a number between 0 and 1:

just <- expand.grid(hjust = c(0, 0.5, 1), vjust = c(0, 0.5, 1))
just$label <- paste0(just$hjust, ", ", just$vjust)

ggplot(just, aes(hjust, vjust)) +
  geom_point(colour = "grey70", size = 5) + 
  geom_text(aes(label = label, hjust = hjust, vjust = vjust))

Note that you can use numbers outside the range (0, 1), but it's not recommended.



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ggplot2 documentation built on May 30, 2017, 2:36 a.m.