"Unused Argument Error"

[swaheera]

I am working with the R programming language. I defined the following function and I am trying to perform the "random search" algorithm on this function.

First, I loaded the library:

#load library : https://cran.r-project.org/web/packages/randomsearch/index.html 

library(randomsearch)

Then, I defined the function:

   # create some data for this example
a1 = rnorm(1000,100,10)
b1 = rnorm(1000,100,10)
c1 = sample.int(1000, 1000, replace = TRUE)
train_data = data.frame(a1,b1,c1)


#define function (4 inputs x[1], x[2], x[3], x[4] and 4 outputs f1, f2, f3, f4)

fn <- function(i) {
    x1 <- x[i,1]; x2 <- x[i,2]; x3 <- x[i,3] ; x4 <- x[i,4]
    f <- numeric(4)
    #bin data according to random criteria
    train_data <- train_data %>%
        mutate(cat = ifelse(a1 <= x1 & b1 <= x3, "a",
                            ifelse(a1 <= x2 & b1 <= x4, "b", "c")))
    
    train_data$cat = as.factor(train_data$cat)
    
    #new splits
    a_table = train_data %>%
        filter(cat == "a") %>%
        select(a1, b1, c1, cat)
    
    b_table = train_data %>%
        filter(cat == "b") %>%
        select(a1, b1, c1, cat)
    
    c_table = train_data %>%
        filter(cat == "c") %>%
        select(a1, b1, c1, cat)
    
    
    #calculate  quantile ("quant") for each bin
    
    table_a = data.frame(a_table%>% group_by(cat) %>%
                             mutate(quant = ifelse(c1 > 150,1,0 )))
    
    table_b = data.frame(b_table%>% group_by(cat) %>%
                             mutate(quant = ifelse(c1 > 300,1,0 )))
    
    table_c = data.frame(c_table%>% group_by(cat) %>%
                             mutate(quant = ifelse(c1 > 400,1,0 )))
    
    f1 = mean(table_a$quant)
    f2 = mean(table_b$quant)
    f3 = mean(table_c$quant)
    
    
    #group all tables
    
    final_table = rbind(table_a, table_b, table_c)
    # calculate the total mean : this is what needs to be optimized
    
    f4 = mean(final_table$quant)
    
    #add some constraints
    if((x3 - x1) < 0. | (x4 - x2) < 0.) {
        f[1] <- NaN
        f[2] <- NaN
        f[3] <- NaN
        f[4] <- NaN
        
    }
    
    return (f)
}

Finally, I tried to run the "random search" algorithm on this function:

#run algorithm
res = randomsearch(fn, lower = c(80, 80, 80, 80), upper = c(100,120,100,120), minimize = c(TRUE, TRUE, TRUE, TRUE), max.evals = 30)
rs = summary(res)

But this resulted in the following error:

Error in fun(x, ...) : unused argument (x)

Does anyone know why this error is being produced? Is it related to the way I have defined the function "fn"?

Thanks

[swaheera]

Note: I was able to get this code to run on a simpler function:

library(randomsearch)

fun_1  <- function(x) {
        var_1 <- sin(x[1] + x[2])
        var_2 <- cos(x[1] - x[2])
        var_3 <- x[2] + x[4]
        var_4 <- x[3] + x[4] -7
        goal_1 = sum(var_1 + var_2 + var_3 + var_4)
        goal_2 = var_1 - var_2 + var_3 + var_4
       
        if (var_1 > 0.6 ) {
            goal_1 = 111111111111111111111111111 }
        else {
            goal_1 = sum(var_1 + var_2 + var_3 + var_4)
        }
       
        return(c(goal_1, goal_2))
       
    }

res = randomsearch(fun_1, lower = c(0, 0, 0, 0), upper = c(100,100,100,100), minimize = c(TRUE, TRUE), max.evals = 30)
rs = summary(res)

Now, view the results:

head(rs)
Randomsearch Result: 
Multiobjective Search Pareto Front 
        y_1      y_2       x1       x2       x3       x4
30 50.88336 52.88124 69.40536 47.46023 0.458284 5.775114