Helper function to produce nice breaks on logarithmic axes

This is needed when the logarithmic y-axis spans less than one order of magnitude, in which case the ggplot2 default produces no ticks.

log_breaks(n = 6)

Arguments

n	Approximate number of ticks

Value

A function that can be used as the break argument in calls to scale_y_continuous() or scale_x_continuous()

Details

Thanks to Heather Turner at https://stackoverflow.com/questions/14255533/pretty-ticks-for-log-normal-scale-using-ggplot2-dynamic-not-manual