How can I extract plot axes' ranges for a ggplot2 object?

I have an object from ggplot2, say myPlot, how can I identify the ranges for the x and y axes?

It doesn't seem to be a simple multiple of the data values' range, because one can rescale plots, modify axes' ranges, and so on. findFn (from sos) and Google don't seem to be turning up relevant results, other than how to set the axes' ranges.

Solution 1:

In newer versions of ggplot2, you can find this information among the output of ggplot_build(p), where p is your ggplot object.

For older versions of ggplot (< 0.8.9), the following solution works:

And until Hadley releases the new version, this might be helpful. If you do not set the limits in the plot, there will be no info in the ggplot object. However, in that case you case you can use the defaults of ggplot2 and get the xlim and ylim from the data.

> ggobj = ggplot(aes(x = speed, y = dist), data = cars) + geom_line()
> ggobj$coordinates$limits

$x
NULL

$y
NULL

Once you set the limits, they become available in the object:

> bla = ggobj + coord_cartesian(xlim = c(5,10))
> bla$coordinates$limits
$x
[1]  5 10

$y
NULL

Solution 2:

I am using ggplot2 version 2, I am not sure if this is same is previous version, Suppose you have saved your plot on plt object. It is easy to extract the ranges,

# y-range
layer_scales(plt)$y$range$range

# x-range
layer_scales(plt)$x$range$range

In case of facet plot, you can access scales of individual facets using layer_scales(plot, row_idx, col_idx). For example to access the facet at first row and second column,

# y-range
layer_scales(plt, 1, 2)$y$range$range

# x-range
layer_scales(plt, 1, 2)$x$range$range

Solution 3:

November 2018 UPDATE

As of ggplot2 version 3.1.0, the following works:

obj <- qplot(mtcars$disp, bins = 5)

# x range
ggplot_build(obj)$layout$panel_params[[1]]$x.range

# y range
ggplot_build(obj)$layout$panel_params[[1]]$y.range

A convenience function:

get_plot_limits <- function(plot) {
    gb = ggplot_build(plot)
    xmin = gb$layout$panel_params[[1]]$x.range[1]
    xmax = gb$layout$panel_params[[1]]$x.range[2]
    ymin = gb$layout$panel_params[[1]]$y.range[1]
    ymax = gb$layout$panel_params[[1]]$y.range[2]
    list(xmin = xmin, xmax = xmax, ymin = ymin, ymax = ymax)
}
get_plot_limits(p)

Until the next update...

Solution 4:

Get the yrange with

ggplot_build(myPlot)$panel$ranges[[1]]$y.range

and the xrange with

ggplot_build(myPlot)$panel$ranges[[1]]$x.range

Solution 5:

In version 2.2.0 this has to be done as follows:

# y-range
ggplot_build(plot.object)$layout$panel_ranges[[1]]$y.range
# x-range
ggplot_build(plot.object)$layout$panel_ranges[[1]]$x.range