10.4.4 Saving as an image

• Getting relative sizes of text, titles, labels and chart can be challenging.

• Use rel() for relative sizes in your custom theme.

• Set parameters for code chunks.

theme_bw(base_size = 14) %+replace%
    theme(
      # The figure
      plot.title = element_text(size = rel(1)),
      
      # Remove the minor gridlines and border
      panel.grid.minor = element_blank(),
      panel.border = element_blank(),
      
      # Specify the axes
      axis.title = element_text(size = rel(0.90)),
      axis.text = element_text(size = rel(0.80)),

      # The legend
      legend.title = element_text(size = rel(0.80)),
      legend.text = element_text(size = rel(0.70)),
      legend.key = element_rect(fill = "transparent",
                                colour = NA),
      legend.background = element_rect(fill = "transparent",
                                       colour = NA)
    )

• Within a code chunk:

  • fig.asp - from 0 to 1.

  • fig.width - integer.

  • fig.height - integer.

  • out.width - a percentage.

  • out.height - a percentage.

knitr::opts_chunk$set(
 fig.width = 5,
 fig.asp = 0.7,
 out.width = "75%"
)

Finally…

ggsave("lineplot.png", plot = lineplot2, width = 6, height = 4)