Using R script Write a program implement a simple Phone Book § The goal is to cr

Question

Using R script Write a program implement a simple Phone Book § The goal is to create an end-user application that users can use to manage friend's data and contact information § You are the developer of the application, not the user There are many friends § Sometimes you make new friends § Sometimes you unfriend someone § For each friend we want to remember § Last name § First name § Phone number Implement the following functionality: § Print a friend's info § Print the whole telephone book § Insert a friend's info § Delete a friend's info § Look-up a friend's info § Use only vectors and simple data types (e.g. text, numeric)

Explanation / Answer

Only vectors have been used to realise the problem.

GetName <- function(){
   cat("Enter last name: ")
   lname <- readLines("stdin", n = 1);

   cat("Enter first name: ")
   fname <- readLines("stdin", n = 1);
  
   return <- paste(lname, fname)
}

Telephone_Print <- function() {
   for (v in seq_along(names)) {
       cat(names[v], " ", contacts[v], " ")
   }
}

Friend_Info <- function(lname, fname) {
   name <- GetName()
   toprint <- which(names == name)
   if(length(toprint) == 0)
       cat(name, "not found", " ")
   for (v in toprint) {
       cat(names[v], " ", contacts[v], " ")
   }
}

Friend_New <- function() {
  
   name <- GetName()
   cat("Enter contact info: ")
   contact <- readLines("stdin", n = 1);
  
   names <<- c(names, name)
   contacts <<- c(contacts, contact)
}

Friend_Unfriend <- function(){
   name <- GetName()
   todel <- which(names == name)
   if(length(todel) > 0){
       names <<- names[-(todel)]
       contacts <<- contacts[-(todel)]
   }
}

names <- c()
contacts <- c()
destfile <- "data.rda"
if(file.exists(destfile)){
   load(file = destfile)
}

while(TRUE){
   writeLines(" #Menu 1. Add a friend 2. Delete a friend 3. Friend info 4. Print telephone book 5. Exit")
   cat("Choose an action:")
   action <- readLines("stdin", n = 1);
   cat(" ")
   if(action == 1){
       Friend_New()
   } else if(action == 2){
       Friend_Unfriend()
   } else if(action == 3){
       Friend_Info()
   } else if(action == 4){
       Telephone_Print()
   } else if(action == 5){
       cat("Saving data Exitting ")
       save(names, contacts, file = destfile)
       quit()
   } else{
       print("Wrong choice, try again!")
   }
}

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