How to curve a line in regression( geom smooth) in r

Question

ggplot(data = wheatX, 
       aes(x = No.of.species, 
       y = Weight.of.weed,
       color = Treatment)) + 
   geom_point(shape = 1) + 
   scale_colour_hue(l = 50) + 
   geom_smooth(method = glm,
               se = FALSE)

This draws a straight line. But the species number will decrease at somepoint. I want to make the line curve. How can I do it. Thanks

[How to make a great R reproducible example?](http://stackoverflow.com/questions/5963269) — zx8754, Jul 20 '16 at 08:30

score 1 · Answer 1 · answered Jul 20 '16 at 09:58

This is going to depend on what you mean by "smooth"

One thing you can do is apply a loess curve:

ggplot() + ... + stat_smooth(method = "loess", formula = biomass ~ numSpecies, size = 1)

Or you can manually build a polynomial model using the regular lm method:

ggplot() + ... + stat_smooth(method = "lm", formula = biomass ~ numSpecies + I(numSpecies^2), size = 1)

You'll need to figure out the exact model you want to use for the second case, hence what I originally meant by the definition of the term "smooth"

How to curve a line in regression( geom smooth) in r

1 Answers1