stat_function and grid.arrange in for loop

Question

I'm trying to plot multiple functions with ggplot2 package using stat_function. As I have several parameters' options I use for loop. I save my plots into list variable myplot. The problem arises when I try to print them. Using print everything seems OK, but when I use only option e.g. myplot[[1]] the lines are the same as for myplot[[2]] etc, however points are plotted correctly. The same issue can be observed when I try to plot all my graphs with one figure using function grid.arrange.

See my example:

library("ggplot2")
myfun <- function(x, group, a, b, e){
  a * x + b + group * e
}
abe <- rbind(c(1, 2, 3), c(7, 0, -4), c(-1, -5, 8))
myplot <- list()
for (i in 1:3){
  x1 <- rnorm(10, 0, 1)
  x2 <- rnorm(10, 1, 1)
  num <- runif(20, -10, 10)
  df <- cbind(rbind(data.frame(x = x1, group = "group 1"), 
                    data.frame(x = x1, group = "group 2")), 
              num) 
  myplot[[i]] <-  ggplot(df, aes_string("x", "num")) +
                  geom_point(aes_string(colour = "group")) + 
                  stat_function(aes(colour = "group 1"),
                                fun = function(x) 
                                myfun(x, 0, abe[i, 1], abe[i, 2], abe[i, 3]),
                                geom = "line") +
                  stat_function(aes(colour = "group 2"),
                                fun = function(x) 
                                myfun(x, 1, abe[i, 1], abe[i, 2], abe[i, 3]),
                                geom = "line") + 
                  ylim(c(-10, 10)) + xlim(c(-2, 2)) 
}

### everything OK
for (i in 1:3){
  print(myplot[[i]])
}
### points are changing but lines remain the same
myplot[[1]]; myplot[[2]]; myplot[[3]]
### again points are changing but lines remain the same
grid.arrange(myplot[[1]], myplot[[2]], myplot[[3]], ncol = 3)

As I want to save all figures into one file I would love to make grid.arrange plot lines correctly.

Roland · Accepted Answer · 2016-08-09 13:57:15Z

When you print the plots, i == 3 and your function evaluates the parameters only then and with this value of i. Use the proper stat_function syntax instead:

myplot[[i]] <-  ggplot(df, aes_string("x", "num")) +
    geom_point(aes_string(colour = "group")) + 
    stat_function(aes(colour = "group 1"),
                  fun = myfun,
                  args = list(a = abe[i, 1], b = abe[i, 2], 
                              e = abe[i, 3], group = 0),
                  geom = "line") +
    stat_function(aes(colour = "group 2"),
                  fun = myfun,
                  args = list(a = abe[i, 1], b = abe[i, 2], 
                              e = abe[i, 3], group = 1),
                  geom = "line") + 
    ylim(c(-10, 10)) + xlim(c(-2, 2))

Collectives™ on Stack Overflow

stat_function and grid.arrange in for loop

1 Answer 1

Comments

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Related