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
)Name of the plot file to generate.
Plot to save.
Number of subplot columns.
Number of subplot rows.
The height (in inches) of the plot or of one sub-plot if nrow
or ncol > 1. Default is 3.71.
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.
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().
Deprecated. Use ncol.
Deprecated. Use nrow.
Deprecated. Use base_asp.
Deprecated. Don't use.
Deprecated. Don't use.
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.
# \donttest{
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()
file1 <- tempfile("file1", fileext = ".png")
file2 <- tempfile("file2", fileext = ".png")
save_plot(file1, p1)
# same as file1 but determine base_width given base_height
save_plot(file2, 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()
file3 <- tempfile("file3", fileext = ".pdf")
save_plot(file3, 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")
file4 <- tempfile("file4", fileext = ".pdf")
save_plot(file4, p4, ncol = 2, base_asp = 1.1)
# }