How to pass column name in ggplot facet_wrap in a function

Question

How to pass column name of a data frame in ggplot facet_wrap or fill/colour in a function? I looked up lazyeval but didn't figure out a way.

x="class"
ggplot(mpg, aes(displ, hwy, col=x)) + geom_point() + facet_wrap(x)

In this example, why didn't the points get coloured by x?

Possible duplicate of http://stackoverflow.com/questions/21588096/pass-string-to-facet-grid-ggplot2 or http://stackoverflow.com/questions/11028353/passing-string-variable-facet-wrap-in-ggplot-using-r — akrun, Apr 02 '17 at 13:30

Mamoun Benghezal · Answer 1 · 2017-04-02T13:41:10.697

2

I used an example from ggplot2::facet_wrap. So, you can easily replace ~class with x containing a character or a formulae. Example :

library(ggplot2)
x="class"#or ~class
ggplot(mpg, aes(displ, hwy)) +
        geom_point() +
        facet_wrap(x)

edited Apr 02 '17 at 13:41

answered Apr 02 '17 at 13:28

Mamoun Benghezal

indeed. but how about color each facet? this doesn't seem to work. ggplot(mpg, aes(displ, hwy, col=x)) + geom_point() + facet_wrap(x) thank you – santoku Apr 02 '17 at 13:40
What do you mean by colouring each facet ? The points or the background ? – Mamoun Benghezal Apr 02 '17 at 13:44
the points, as in the snippet ggplot(mpg, aes(displ, hwy, col=x)) + geom_point() + facet_wrap(x) – santoku Apr 02 '17 at 13:51
you should use a variable containing an integer or a factor. Try `mpg$class2 – Mamoun Benghezal Apr 02 '17 at 15:32

score 0 · Answer 2 · answered Apr 02 '17 at 18:08

0

Have you tried ggplot(mpg, aes(displ, hwy, col=as.factor(x))) + geom_point() + facet_wrap(~x) ?

answered Apr 02 '17 at 18:08

jesstme

2 Answers2