CODEWITHSUNDEEP
r
Stephen Poole
Stephen Poole

Reputation: 381

How do I apply this for loop over my character vector and output another vector?

The intention of my code is to concatenate the values from the vector v. To do this, I created a function concat with two arguments vector, SID. But for reasons I don't understand,

#A character vector to which other strings will be appended
    
v <- c("R_2wmKOSbPWHl4VtT2","R_2TtslLEVNeHs2r73","R_ZF79IJ60LaxxsuR4","R_3JJDUkrZ07eIwnh5","R_3JrWuv9fsLK6qNx6")

concat <- function(vector,SID){
  
  decrement_append <- "&decrementQuotas=true"
  SID_append <- "?surveyId="
  
  for(i in 1:length(vector)){
    out[i] <- paste0(v[i],SID_append,SID,decrement_append)
  }
  out[i]
}

And:

concat(vector = v,
       SID = "SV_55tYjKDRKYTRNIh")

When I run this, I get:

Error in concat(vector = v, SID = "SV_55tYjKDRKYTRNIh") : 
  object 'out' not found

I've tried it a couple of other ways, such as:

   concat <- function(vector,SID){
  
  decrement_append <- "&decrementQuotas=true"
  SID_append <- "?surveyId="
  
  new_vector <- for(i in 1:length(vector)){
   out[i] <- paste0(v[i],SID_append,SID,decrement_append)
  }
  new_vector
}

But I'm getting the same error.

Upvotes: 1

Views: 1194

Answers (1)

akrun
akrun

Reputation: 886948

The out is not initialized in the function

concat <- function(vector,SID){
   out <- character(length(vector))
  
   decrement_append <- "&decrementQuotas=true"
   SID_append <- "?surveyId="
  
   for(i in 1:length(vector)){
     out[i] <- paste0(v[i],SID_append,SID,decrement_append)
   }
   out
 }

-testing

> concat(v, "SV_55tYjKDRKYTRNIh")
[1] "R_2wmKOSbPWHl4VtT2?surveyId=SV_55tYjKDRKYTRNIh&decrementQuotas=true" "R_2TtslLEVNeHs2r73?surveyId=SV_55tYjKDRKYTRNIh&decrementQuotas=true"
[3] "R_ZF79IJ60LaxxsuR4?surveyId=SV_55tYjKDRKYTRNIh&decrementQuotas=true" "R_3JJDUkrZ07eIwnh5?surveyId=SV_55tYjKDRKYTRNIh&decrementQuotas=true"
[5] "R_3JrWuv9fsLK6qNx6?surveyId=SV_55tYjKDRKYTRNIh&decrementQuotas=true"

paste/paste0 are vectorized. So, looping is not really needed

concat2 <- function(vector,SID){
    
  
    decrement_append <- "&decrementQuotas=true"
    SID_append <- "?surveyId="
  
    
       paste0(v, SID_append,SID,decrement_append)
    

  }

-testing

> concat2(v, "SV_55tYjKDRKYTRNIh")
[1] "R_2wmKOSbPWHl4VtT2?surveyId=SV_55tYjKDRKYTRNIh&decrementQuotas=true" "R_2TtslLEVNeHs2r73?surveyId=SV_55tYjKDRKYTRNIh&decrementQuotas=true"
[3] "R_ZF79IJ60LaxxsuR4?surveyId=SV_55tYjKDRKYTRNIh&decrementQuotas=true" "R_3JJDUkrZ07eIwnh5?surveyId=SV_55tYjKDRKYTRNIh&decrementQuotas=true"
[5] "R_3JrWuv9fsLK6qNx6?surveyId=SV_55tYjKDRKYTRNIh&decrementQuotas=true"

Upvotes: 2

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