One function per facet-CodePudding

I can plot a function in ggplot2, like so:

library(ggplot2)
ggplot(data.frame(x=0), aes(x))   geom_function(fun = sin)   xlim(c(-5,5))

Can I use ggplot2's facetting to make the plot for multiple functions, one in each facet? (for example sin and cos)

CodePudding user response：

Because fun= is not an aesthetic, I think you cannot facet on it. However, you can faux-facet using the

If you prefer the "look" of ggplot2's facets, you can choose this method instead:

gsin <- ggplot(data.frame(x=0, fun="sin"), aes(x))  
  facet_wrap(~fun)  
  geom_function(fun = sin)  
  xlim(c(-5,5))
gtan <- ggplot(data.frame(x=0, fun="tan"), aes(x))  
  facet_wrap(~fun)  
  geom_function(fun = tan)  
  xlim(c(-5,5))
gsin   gtan

All of this so far has the effect of facet_*(scales="free_y") (because we fixed xlim(.)). If you want to mimic faceting more closely, you need to control the limits of all facets:

ylims <- c(-1, 1)
gsin <- ggplot(data.frame(x=0, fun="sin"), aes(x))  
  facet_wrap(~fun)  
  geom_function(fun = sin)  
  xlim(c(-5,5))  
  scale_y_continuous(limits = ylims)
gtan <- ggplot(data.frame(x=0, fun="tan"), aes(x))  
  facet_wrap(~fun)  
  geom_function(fun = tan)  
  xlim(c(-5,5))  
  scale_y_continuous(name = NULL, guide = NULL, limits = ylims)
gsin   gtan
# Warning: Removed 22 row(s) containing missing values (geom_path).

Technically you are not required here to set the y-limits on all, but ... unless you know with certainty that the limits on unconstrained y-axes will be what you need, it is possible that they could be slightly off. For instance, if you change the initial function (in a quick hack) to be 2*sin(x) but forget to update the remaining facets' y-limits, then your plots will be lying. It's best to set the limits in a single place (ylims <- ...) and reference in all plots.

CodePudding user response：

Looks like you in fact can facet by the function if you feed each layer its own data with the faceting variable specified:

library(ggplot2) # using ggplot2 3.3.5
ggplot(data.frame(x=0), aes(x))   
  geom_function(fun = sin, data = data.frame(x = -5:5, fun = "sin"))  
  geom_function(fun = cos, data = data.frame(x = -5:5, fun = "cos"))  
  facet_wrap(~fun)