ggplot2: Single smooth line for several line plots within facets

Question

I want to plot multiple facets with several lines each. In every facet, for the set of line plots, I would like to show a kind of smooth line representing a general trend for all those lines in a given particular facet. Does anybody know if it is possible? I have tried so far something like this:

ggplot(data = mydata, aes(x = x, y = y, group = group)) + geom_line('GRAY') + facet_wrap(~ class) + geom_smooth('loess') (see figure)

However, what I observe is another line for every line plot within each facet, instead of a single line within every facet.

Thanks in advance

Please simulate some data which demonstrates what you have tried and what you're after. That `geom_line()` you are using is probably adding one line. Are you sure you need it? — Roman Luštrik, Oct 24 '16 at 08:34
Take a look at [this question](http://stackoverflow.com/questions/6673074/how-do-i-place-an-identical-smooth-on-each-facet-of-a-ggplot2-object) — Valter Beaković, Oct 24 '16 at 11:57
@ValterBeaković I tried what you suggested, with no changes. Instead, I got the same plot with all categories in every facet. — Paco el Cuqui, Oct 25 '16 at 09:53

score 1 · Answer 1 · edited Apr 20 '19 at 11:46

1

... +
geom_smooth(aes(group=class), method="lm") +
...

Should make one line pr. facet

edited Apr 20 '19 at 11:46

Zoe

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answered Apr 20 '19 at 10:35

pallevillesen

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score 0 · Answer 2 · answered Oct 25 '16 at 10:06

0

This is an example with the iris dataset:

    gg <- ggplot(iris, aes(x = Sepal.Length, y = Petal.Length)) + 
            geom_line() + 
            facet_wrap(~ Species) +
            geom_smooth(data = within(iris, Species <- NULL), fill = "red")
    gg

answered Oct 25 '16 at 10:06

Valter Beaković

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This is not an answer. If you want to help OP (he or she should to it him/herself, though), feel free to edit their question. – Roman Luštrik Oct 25 '16 at 13:24
Maybe I explained myself wrong, but it is not exactly what I'm trying to do. I have multiple lines but within the same facet, and multiple facets. In that example with the iris dataset, you have one line per facet, whereas I have many. – Paco el Cuqui Oct 25 '16 at 13:27
This is why I asked for a sample of the original data set. The iris example was an attempt to help while waiting for the sample.... – Valter Beaković Oct 25 '16 at 13:29

ggplot2: Single smooth line for several line plots within facets

2 Answers2