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I'm trying to create a plot with multiple functions. Each function is defined by coefficients in a data frame, each row of the data frame contains the coefficients for one function and an identifier for the group.

The goal is to have stat_function draw the lines over using coefficients from the data frame, but with no actual data for x. Each line should have a unique colour and be listed in the legend

I have seen examples where several stat_functions are added and the colours are individually defined here. I would like to avoid this to make the function dynamic and be able to plot a variable number of functions with minimal changes.

The answer found here is very close to what I am looking for, however every function has the same colour and there is no legend.

I have managed to output a plot with unique colours and no legend, and with a legend but only one colour.

Here is an example of my plot in ggplot:

library(plyr)

#create data frame

qr <- c(0.11,0.11,0.11,0.05)
qs <- c(0.98,0.98,0.97,0.93)
alpha <- c(78.0564,141.017,58.0405,12.6902)
n <- c(1.53364,1.37685,1.42174,1.15284)
ks <- c(9.936,3.915563,04575,0.312171)
l <- c(-0.09953,-1.5645,-0.12945,2.16382)
m <- 1-1/n
depth <- c(1,2,3,4)

coefs <- data.frame(qr,qs,alpha,n,ks,l,m,depth)

#legend one colour
coeflines1 <-
  alply(as.matrix(coefs), 1, function(coef) {
    stat_function(fun=function(x)
      {coef[1]+(coef[2]-coef[1])/((1+(coef[3]*x)^coef[4])^coef[7])},
      aes(colour = as.factor(depth[1])))
  })

ggplot(data.frame(x=c(0.001, 10)), aes(x=x)) + 
  coeflines1 +
  scale_x_log10()

#no legend multile colour
coeflines2 <-
  alply(as.matrix(coefs), 1, function(coef) {
    stat_function(fun=function(x)
    {coef[1]+(coef[2]-coef[1])/((1+(coef[3]*x)^coef[4])^coef[7])},
    colour = coef[8])
  })

ggplot(data.frame(x=c(0.001, 10)), aes(x=x)) + 
  coeflines2 +
  scale_x_log10()

The problem with the first example is that it is not referencing anything within the functions. If depth[1] is changed to coef[8] I get Error in coef[8] : object of type 'closure' is not subsettable

In the second example no legend appears because I haven't mapped an aesthetic. How can I map an aesthetic that corresponds to the last (8th) column of the data frame coefs?

hydrosphag
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  • What is `alply` in coeflines1 ? Did you mean `apply` ? – MrSmithGoesToWashington Feb 12 '18 at 08:47
  • For the second plot, is it `coeflines2 ` instead of `coeflines ` ? – MrSmithGoesToWashington Feb 12 '18 at 08:48
  • `Error in coef[8] ..` May be you can do it again with `coefs` intead of `coef` and see what happens ... – MrSmithGoesToWashington Feb 12 '18 at 08:52
  • alply is from the plyr package, It slices an Array into a List by row (1). Yes you are correct, the second plot should have coeflines2, I've updated the question to reflect this and added the package. Using `coefs` instead access the entire list instead of position 8 in the array. `coefs[[8]][1]` could be used to get the first element, however it does not iterate through each row. As such, it gives the error 'x' must be atomic for 'sort.list'. – hydrosphag Feb 12 '18 at 15:34

0 Answers0