R: Error in fn(unlist(x), …) : unused argument (unlist(x))

[swaheera]

I am using the "mlrMBO" library in R (CRAN - Package mlrMBO). I am trying to learn how to run an optimization algorithm on some arbitrary function that I defined:

#Load library
library(mlrMBO)

#define objective function
obj.fn = makeMultiObjectiveFunction(
  name = "My test function",
  fn = function(x1, x2, x3, x4) {
    var_1 <- sin(x1 + x2)
    var_2 <- cos(x1 - x2)
    var_3 <- x1 + x4
    var_4 <- x3 + x4 -7
        goal_1 = sum(var_1 + var_2 + var_3 + var_4)
    goal_2 = var_1 + var_2 - var_3 + var_4
    goal_3 = var_1 + var_2 - var_3 + 2*var_4

    return(c(goal_1, goal_2, goal_3))

},
#define acceptable ranges
par.set = makeParamSet(
     makeNumericParam("x1", lower = 20, upper = 40),
     makeNumericParam("x2", lower = 30, upper = 45),
     makeNumericParam("x3", lower = 10, upper = 20),
     makeNumericParam("x4", lower = 10, upper = 50),
#define constraints
    forbidden = expression(x2 >x1 | x3 > x4)
),

minimize=TRUE
)

#create control gird
 control=makeMBOControl(propose.points=1, final.method="best.predicted", final.evals=10)
 control=setMBOControlTermination(control, iters=10)
 control=setMBOControlInfill(control, crit=makeMBOInfillCritEI())

#perform optimization
lrn=makeMBOLearner(control, obj.fun)

This code returns the following error:

Error in fn(unlist(x), ...) : unused argument (unlist(x))

Does anyone know why this error is being produced? I have tried to look at various reference material (e.g. https://cran.r-project.org/web/packages/mlrMBO/mlrMBO.pdf ), but so far I am unable to understand why this error is being produced.

Can someone please show me what am I doing wrong?

Thanks

[nirgrahamuk]

@swaheera

Error in fn(unlist(x), ...) : unused argument (unlist(x))

first, your error relates only to makeMultoObjectiveFunction() call.
It seems you are missing n.objectives, and supplying a suitable minimize param to match.

#define objective function
obj.fn = makeMultiObjectiveFunction(
  name = "My test function",
  fn = function(x1, x2, x3, x4) {
    var_1 <- sin(x1 + x2)
    var_2 <- cos(x1 - x2)
    var_3 <- x1 + x4
    var_4 <- x3 + x4 -7
    goal_1 = sum(var_1 + var_2 + var_3 + var_4)
    goal_2 = var_1 + var_2 - var_3 + var_4
    goal_3 = var_1 + var_2 - var_3 + 2*var_4
    
    return(c(goal_1, goal_2, goal_3))
    
  },
  n.objectives = 3L,
  #define acceptable ranges
  par.set = makeParamSet(
    makeNumericParam("x1", lower = 20, upper = 40),
    makeNumericParam("x2", lower = 30, upper = 45),
    makeNumericParam("x3", lower = 10, upper = 20),
    makeNumericParam("x4", lower = 10, upper = 50)
    #define constraints
   , forbidden = expression(x2 >x1 | x3 > x4)
  ),
  
  minimize=rep(TRUE,3)
)

[swaheera]

Thank yo so much for your answer! After running the corrected version of the code, along with

I tried to execute everything:

res = mbo(obj.fun, design = NULL, learner = lrn, control = ctrl, show.info = TRUE)

But I got this error:

Warning in generateDesign(n.params * 4L, par.set, fun = lhs::maximinLHS) :
  generateDesign could only produce 0 points instead of 16!
Computing y column(s) for design. Not provided.

Error in as.data.frame.OptPathDF(opt.path, include.rest = FALSE) : 
  No elements where selected (via 'dob' and 'eol')!

Do you know why this is happening?

Thank you so much!