geom_pointline has difficulty displaying lines between very close points

[stefanedwards]

The issue first appears when rendering the plots. It does not appear to be a rounding error as changing the distance argument to other units affects the outcome.

library(ggplot2)
library(lemon)

data(sunspot.year)
sunspots <- data.frame(count=as.numeric(sunspot.year), year=seq.int(start(sunspot.year)[1], end(sunspot.year)[1]))
sunspots <- subset(sunspots, year > 1900)

ggplot(sunspots, aes(x=year, y=count)) + geom_pointline(distance=unit(3, 'pt')) + labs(main='geom_pointline')
pointline

It can as best be described that if the offset 'connector point' of a point extends past the corresponding 'connector point' in the connecting point, in either horisontal or vertical distance, this appears. But determining whether this is the case is difficult because comparisons of unit cannot be done.