This function replaces the standard ggsave() function for saving a plot into a file. It has several advantages over ggsave(). First, it uses default sizes that work well with the cowplot theme, so that frequently a plot size does not have to be explicitly specified. Second, it acknowledges that one often first develops individual plots and then combines them into multi-plot figures, and it makes it easy---in combination with plot_grid()---to carry out this workflow. Finally, it makes it easy to adjust the aspect ratio of the figure, which is frequently necessary to accommodate plots with or without figure legend.

save_plot(filename, plot, ncol = 1, nrow = 1, base_height = 3.71,
  base_asp = 1.618, base_width = NULL, ..., cols, rows,
  base_aspect_ratio, width, height)

Arguments

filename

Name of the plot file to generate.

plot

Plot to save.

ncol

Number of subplot columns.

nrow

Number of subplot rows.

base_height

The height (in inches) of the plot or of one sub-plot if nrow or ncol > 1. Default is 3.71.

base_asp

The aspect ratio (width/height) of the plot or of one sub-plot if nrow or ncol > 1. This argument is used if base_width = NULL or if base_height = NULL; if both width and height are provided then the aspect ratio is ignored. The default is 1.618 (the golden ratio), which works well for figures with a legend.

base_width

The width (in inches) of the plot or of one sub-plot if nrow or ncol > 1. Default is NULL, which means that the width is calculated from base_height and base_aspect_ratio.

...

Other arguments to be handed to ggsave2().

cols

Deprecated. Use ncol.

rows

Deprecated. Use nrow.

base_aspect_ratio

Deprecated. Use base_asp.

width

Deprecated. Don't use.

height

Deprecated. Don't use.

Details

The key idea for this function is that plots are often grids, with sup-plots at the individual grid locations. Therefore, for this function we specify a base width and aspect ratio that apply to one sup-plot, and we then specify how many rows and columns of subplots we have. This means that if we have code that can save a single figure, it is trivial to adapt this code to save a combination of multiple comparable figures. See examples for details.

Examples

library(ggplot2) # save a single plot with a legend p1 <- ggplot(mpg, aes(x = cty, y = hwy, color = factor(cyl))) + geom_point(size = 2) + theme_half_open() save_plot("p1.png", p1) # same as p1 but determine base_width given base_height save_plot("p2.png", p1, base_height = NULL, base_width = 6) # save a single plot without legend, adjust aspect ratio x <- (1:100)/10 p3 <- ggplot(data.frame(x = x, y = x*sin(x)), aes(x, y)) + geom_line() + theme_minimal_hgrid() save_plot("p3.pdf", p3, base_asp = 1.1) # now combine with a second plot and save p3b <- ggplot(data.frame(x = x, y = cos(x)+x), aes(x, y)) + geom_line() + theme_minimal_hgrid() p4 <- plot_grid(p3, p3b, labels = "AUTO") save_plot("p4.pdf", p4, ncol = 2, base_asp = 1.1)