CODEWITHSUNDEEP
r
user3121788
user3121788

Reputation: 45

R: Create a function with optional parameters without if statement

I want to create a function with optional parameters. I am working on a dataset with income, states, and a few flags. The function takes the data, state and flag and filters it. If state and flag is missing, it should return the entire data, and so on. So far I have this code which is working fine. However, I want to know if there is a simpler code than this.

myfun <- function(data, states, flag){
  if(missing(states)) {
    if(missing(flag)) {
      new_data <- data
    } else {
      new_data <- subset(data, data$Flag == flag)
    }
  } else if(missing(flag)) {
    new_data <- subset(data, data$State == states)
  } else {
    new_data <- subset(data, (data$State == states & data$Flag == flag))
  }

  temp_data <- toJSON(new_data)
  save(temp_data, file = "Mydata.JSON")
  return(new_data)      
}

I know we can have optional parameters by having a default parameter like flag = Y. But how do I pass both the parameters in default parameters i.e. flag = Y & N, or all the 50 states. I am new to R and any help would be greatly appreciated.

Update: Got a solution I was looking for thanks to Daniel Winkler

test2 <- function(data,states = unique(data$State),flag = c("Y","N"))
{my_data<-subset(data, (data$State %in% states & data$Flag %in% flag))}

Upvotes: 2

Views: 89

Answers (1)

Daniel Winkler
Daniel Winkler

Reputation: 497

For passing multiple values to the function:

myfun<-function(data,states,flag){


if(missing(states))
  {
    if(missing(flag))
    {
      new_data<-data
    }
    else
    {
      new_data<-subset(data, data$Flag %in% flag)
    }
  }     
  else if(missing(flag))
  {
    new_data<-subset(data, data$State %in% states)
  }
  else
  {
    new_data<-subset(data, (data$State %in% states & data$Flag %in% flag))
  }

  temp_data <- toJSON(new_data)
  save(temp_data, file="Mydata.JSON")
  return(new_data)      
}

Then call with:

all_states <- unique(mydata$States)
myfun(data = mydata, states = all_states, flag = c('Y', 'N'))

Upvotes: 1

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