Failed attempt to store values imputed from a function

Question

Help guys, I'm trying to Impute missing values using a function, the function itself works in this respect, but fails to store the imputed values.

The following shows the function, gh_Df is the dataset; val is the value in FacilityName variable and lat and long are the respective values I hope to fill.

fill_lat_long_na <- function(val, lat, long){
  if(is.na(gh_Df[gh_Df$FacilityName == val,]$Latitude)){
    gh_Df[gh_Df$FacilityName == val,]$Latitude <- lat
    gh_Df[gh_Df$FacilityName == val,]$Longitude <- long
  
    
  }
   print(gh_Df[gh_Df$FacilityName == val,])
}

## Check
fill_lat_long_na("Yapesa St.Mary Clinic", 6.43011, -1.33299)

Results

Latitude	Longitude
6.43011	-1.33299

However if I go back and run the following outside the function it still shows the empty / NA rows.

print(gh_Df[gh_Df$FacilityName == "Yapesa St.Mary Clinic",])

Results

Latitude	Longitude
NA	NA

Is there a way to go about this and the values actually change within the dataset?

Thanks.

Answer 1

Usually it is not a good practice to change a dataframe from inside the function. You can return the changed dataframe and save it outside the function.

fill_lat_long_na <- function(val, lat, long){
  if(is.na(gh_Df[gh_Df$FacilityName == val,]$Latitude)){
    gh_Df[gh_Df$FacilityName == val,]$Latitude <- lat
    gh_Df[gh_Df$FacilityName == val,]$Longitude <- long
  }
  return(gh_Df)
}

gh_Df <- fill_lat_long_na("Yapesa St.Mary Clinic", 6.43011, -1.33299)
gh_Df