r - ggplot2 colour geom_point by factor but geom_smooth based on all data -

in ggplot2, following command p <- qplot(wt, mpg, data=mtcars, colour=factor(cyl)) taken here plots scatter plot each point coloured according factor

i fit data geom_smooth irrespective of factor keeping colour of individual points according factor. p + geom_smooth(method="lm") linear fit on each factor. how do this?

you can stepping 'qplot' wrapper function , using 'ggplot' , geometry functions directly.

ggplot(mtcars, aes(x=wt, y=mpg)) +     geom_point(aes(colour=factor(cyl))) +     geom_smooth(method="lm") 

step 1: set initial 'ggplot' settings. these settings want defaults geometry functions.

ggplot(mtcars, aes(x=wt, y=mpg)) 

in case, using 'mtcars' data geometries 'wt' assigned x-axis , 'mpg' assigned y-axis. specifying these @ beginning, lessen risk of messing when copy-pasting geometry functions.

step 2: draw point geometry, using factors of 'cyl' color points. original 'qplot' function doing, we're specifying little more explicitly.

    geom_point(aes(colour=factor(cyl))) 

step 3: draw smoothed linear model. op wrote before, aesthetic of coloring no longer part of defaults, model draws intended.

    geom_smooth(method="lm") 

chain + et voila!

for reference: being explicit in each layer, so:

ggplot() +     geom_point(data=mtcars, aes(x=wt, y=mpg, colour=factor(cyl))) +     geom_smooth(data=mtcars, method="lm", aes(x=wt, y=mpg))