来自purrr的map中的if条件

Question

I am trying to create a new character vector in R based on the input value present in 'operator' character vector. The operator variable contains values like ">", "<" "" and NULL. I need to create a new vector like operator_id which has equivalent numeric code for the above mathematical operators. Please find the code that I wrote using for loop. However this is very time consuming and is there any other efficient way of writing this code?

for (ch in operator){
  if (ch == ""){
    #print("hi")
    operator_concept_id = append(operator_concept_id, 4172703L)
    value_as_concept_id = append(value_as_concept_id, 45884084L)
  } else if (ch == ">"){
    #print("hello")
    operator_concept_id = append(operator_concept_id, 4172704L)
    value_as_concept_id = append(value_as_concept_id, 45876384L)
  } else if (ch == "<"){
    #print("less")
    operator_concept_id = append(operator_concept_id, 4171756L)
    value_as_concept_id = append(value_as_concept_id, 45881666L)
  }
  else if(ch== "-"){
    #print("negative")
    operator_concept_id = append(operator_concept_id, 4172703L)
    value_as_concept_id = append(value_as_concept_id, 45878583L)
  } else{
    #print("nothing")
    operator_concept_id = append(operator_concept_id, 0L)
    value_as_concept_id = append(value_as_concept_id, 45881630L)
  }
}

Answer 1

Hopefully I got the aim right, this is a possible solution:

Operators<-c(">","<","NULL")#Did not use a real `NULL`
Numerics<-c(1234,567,8910)
purrr::map2(Operators,Numerics,function(x,y) append(x,y))

Result:

#[[1]]
#[1] ">"    "1234"

#[[2]]
#[1] "<"   "567"

#[[3]]
#[1] "NULL" "8910"

Answer 2

We could use a switch statement:

for (ch in operator){
  switch(ch, 
         ">"={
           #print("hello")
           operator_concept_id = append(operator_concept_id, 4172704L)
           value_as_concept_id = append(value_as_concept_id, 45876384L)   
         },
         "<"={
           #print("less")
           operator_concept_id = append(operator_concept_id, 4171756L)
           value_as_concept_id = append(value_as_concept_id, 45881666L)
         },
         "-"={
           #print("negative")
           operator_concept_id = append(operator_concept_id, 4172703L)
           value_as_concept_id = append(value_as_concept_id, 45878583L) 
         },
         {
           #print("hi")
           operator_concept_id = append(operator_concept_id, 4172703L)
           value_as_concept_id = append(value_as_concept_id, 45884084L)
         }
  )

}

Note that we cannot switch on "" , instead, I used that as the default option at the end, so anything not fitting the previous cases will execute as that option.