# "Unused Argument Error"

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

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
``````

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