Force the origin to start at 0

Question

How can I set the origin / interception of the y-axis and x-axis in ggplot2?

The line of the x-axis should be exactly at y=Z.

With Z=0 or another given value.

Answer 1

xlim and ylim don't cut it here. You need to use expand_limits, scale_x_continuous, and scale_y_continuous. Try:

df <- data.frame(x = 1:5, y = 1:5)
p <- ggplot(df, aes(x, y)) + geom_point()
p <- p + expand_limits(x = 0, y = 0)
p # not what you are looking for

p + scale_x_continuous(expand = c(0, 0)) + scale_y_continuous(expand = c(0, 0))

You may need to adjust things a little to make sure points are not getting cut off (see, for example, the point at x = 5 and y = 5.

Answer 2

I understand from Hadley Wickham's answer in the link here that it is not possible in ggplot2 to have the axes in the middle of your graph. Someone in that url proposed to remove the standard axes and build them yourself.